Anime Missed opportunities
To quote Obi-Wan: "You were the chosen one". Coming from Fate/Zero and Kara no Kyoukai, many people, me included had great expectation for Unlimited Blade Works. However, unlike its forefathers, UBW barely scratches the tip of its source material. Well yes the core plot remained, but you could say the same thing about the awful DEEN adaptation done in 2006 (ignore the other review by the way, he is a well known forum troll on MAL and Crunchyroll). Its flashy, it wowed people and introduced Fate/Stay Night to the mass.... but that's all it is.
In trying to keep it fresh for VN readers, Kinoko Nasu (and co.) created a tough pill to swallow for both the veteran and the newcomers. Your everyday CR viewers will be woah and wowed by the "hype" and "budget", but the seasoned critic easily pointed out issues in characterization (shallow, 2d characters) and plot (the VN used the cliched plot as a medium to deconstruct Shirou's ideal). VN readers either saw it as a way to get their favorite fights animated, or a complete failure that made the same mistakes DEEN made nearly a decade ago.
If this was the first adaptation, it could've been accepted as a "promote the source material" type of anime, similar to the 2006 adaptation (which was made in conjunction with the voiced sex-less PS2 edition), but as a standalone from a company with an impressive track record, it is a flub.
TL;DR: Read the VN, watch it for comparison, the extra stuffs and fights being animated.
And just a minor note, just because the original author worked on it, doesn't mean its as good as the original. Shitty sequels are common, and while this technically isn't a sequel, it doesn't really hold up to the original
Anime A worthy series on its own merits
Adaptations tend to be judged in comparison to the original work, and not whether certain aspects of them are good or bad story decisions in and of themselves. Unlike some of the other reviews, I will focus on whether the Unlimited Blade Works anime is a good series by itself, and in a word, it is.
Fate/stay night is a Visual Novel about seven mages and their servants battling it out for the control of the Holy Grail. This series adapts the Unlimited Blade Works route, in which Shirou falls in love with his fellow MasterRin, as he fights alongside her.
The as a good amount of twists and turns, which help keep things interesting. There isn't quite as much of the backstabbing, scheming and intricate planning as in Fate/Zero, but it's enjoyable to see various characters' plans come into conflict with those of others. Through it all, the tone is fairly dark, but things are never absolutely hopeless, and while characters often pay the price for their ideals and principles, having them is not necessarily considered a bad thing.
The animation quality is top notch, leading to some excellent fight scenes. The soundtracks also are of similar quality, which nicely adds to the experience.
The characters are generally nicely fleshed out, well developed and given good reasons behind their actions. Unfortunately, you may notice that many of those from the high school segment disappear from the story before long. While this is mostly a case of Shoo Out the Clowns, if you saw Fate/Zero(or read the original VN) you'll know that Sakura is much more significant than Shirou's kouhai and frequent houseguest, but doesn't get to do much here. Part of the problem is that she mainly features in Heaven's Feel, and it's difficult for adaptations of visual novels to cover other routes, but it seems like a wasted opportunity, considering that there are a few hints about Sakura being Rin's sister.
Speaking of the visual novel, I'm familiar with it to some degree, but haven't played through it enough to judge the anime's faithfulness as an adaptation, but believe that this anime is excellent on its own merits. If you're looking for a place to start with the Fate/stay night series, or for an entertaining anime series, Unlimited Blade Works is well worth your time.
Anime Deen's version is far superior
And ufotable does it once again largely focusing on style over substance. Not much to say about this series other than just don't watch it. What the f is with Shiro's outfit?! What the f is with all the character art?! they look like barbie doll/bobble head hybrids. also they skipped out on a scene that was an actual cg in the vn. which would've been fine if they didn't do a near hour long prologue. but they did so it's just lazy on pukotable's part. And compared to the first anime it could still use a lot of work.
Deen's version was way better. This one is following the Visual Novel a little too closely. I consider something garbage when it's an adapation that can't come up with its own stuff. At this rate I'd rather just watch the old one again. Comparing the first couple episodes of both series 2006 is much more well done while the new one is little over decent and it's already nearing being crap. But then again you gotta keep your expectations low with ufotable especially when comparing them with Deen who knows the value of substance over style. So if you're looking for a good FSN adaptation watch the orginal anime, you'll be left with a much better taste in your mouth.
Anime Beautiful
There is only one word to describe this series, beautiful. The art, the music, the animation everything! Everything shows effort and well thought out planning. The anime is very faithful to the Visual novel and has added some extra foreshadowing/original content for added fun. With animation even better than Fate/Zero, it's impossible to call this series ugly. Ufotable shows a deep understanding of the source material being able to effectively covert Fate/Stay Night from VN to anime. The only real possible strikes against this series is if you hated the Unlimited Blade Works route and some odd angling in Episode 2
Anime Worst in the Franchise
And by "worst" I really mean mediocre. Compared to the other installments, UBW comes across as vanilla. Mainly due to the awful pacing, Archer, Rin, Shirou, and the frustrating and laughable handling of its themes.
To be clear, Rin is a good supporting character, but not a good lead, at least compared to Sakura and Saber, as Rin's "dead parents" backstory comes across as tame compared to their routes. It doesn't help that I was ecstatic when her parents died. Her tsundere attitude got annoying incredibly quickly since Shirou's neither a pervert nor an idiot. And their romance was half-baked, having no chemistry and no obstacles to overcome. In addition to the immense hype she gets, the fact that Archer gets more focus than her doesn't help either.
As for Archer, well, he's a dick. Not a charismatic dick, but the kind you wish would shut up because he sounds like a complete tool. His sarcasm and teasing was groan-inducing. It doesn't help that he's portrayed as being pragmatic despite being a dumbass. He keeps railing on and on about how ideals can never be achieved and therefore are worthless. My reaction to it was "no shit, Sherlock, but so what?" Archer's the type of guy who reads a Superman comic and instead of enjoying it and understanding the message, he says "this isn't realistic at all!" It gets to the point where he sounds like a big crybaby because he didn't succeed. He justifies many of his choices saying it'll save more lives down the road which is straight-up bullshit. Believing Berserker and Illya to be the bigger threat despite them being rather neutral, if sadistic and annoying, in the grand scheme of things, at least that's what I got from it. Overall, he's just insufferable, especially so when he agrees to let Shinji do as he pleases with Rin's body, although he does tell him he can do so only when she's no longer usefulness, which isn't any better. And yet, for some reason, Rin still sympathizes with the douche.
And the pacing, all I have to say is there's three 50 minute episodes out of 25 episodes, some of which are almost 30 minutes. And in that additional time, absolutely nothing happens. For example, the prologue gives us no insight into Rin, you could remove that episode and it changes nothing. Waste of time.
Shirou's arc is merely him reaffirming his beliefs and getting stronger, none of which happen gradually, and the latter broke my suspension of disbelief. There's no sufficient explanation given as to why he's now able to be super badass and go toe-to-toe with people who've trained all their life or have been shown to be immensely more powerful. As for the exploration of his beliefs, it's awkward and drawn out. To be fair, Fate's always been shit at the whole philosophical aspect. It can be summed up as everyone telling Shirou he's an idiot/naïve for 25 episodes, only for him in the climax to finally respond back with "I don't care." Truly epic.
UBW isn't bad, it's just unnecessary.