Webcomic Good start and getting better.
You have to give Collar 6 credit for one thing. How many other webcomics out there have tried to blend BDSM and shounen tropes into an enjoyable mix? Does it work? I think so, but let's look at the good and bad.
The good is the art and the story. The comic undergoes some rapid Art Evolution, from a basic newspaper format to color to full pages in just a few months and has maintained that since. There's an appropriate level of detail to all things and it's very clean and colorful. The story, while initially a little rough, also improves, albeit a bit more gradually, as the characters are developed and the world they live in is fleshed out. The plot holes and more questionable actions are rather well explained away and justified without being too far-fetched or contrived.
There are two faults I find with the comic. The first is the beginning, as it feels a little like it doesn't know what comic it wants to be, going rather quickly from comedy to drama to shounen and back again until the characters stop and start developing. Nothing major, but it might be a little annoying for new readers. The second fault is that, due to the still-developing nature of the world, exposition can sometimes feel like a Info Dump that causes the plot to come to a halt. While still relatively entertaining as well as informative, hopefully these will be less frequent as the world finishes fleshing out.
Overall, I'd say if you both BDSM and shounen, you'll probably enjoy this comic overall. If you like one and can tolerate the other, you can at least give a look to see if it's your taste or not.
Webcomic EDIT: There was an attempt
It appears I can't delete reviews attached to a screen name that I'm now attached to, and that no longer represent my views. But I can edit them! So let's give this another go.
Collar 6 takes place in a barmy alternate universe in which BDSM gives people superpowers, and the whole world has adapted itself to revolve around it. This concept is actually kind of neat, but there are a number of problems.
First of all, it's like the comic doesn't know what it wants to be. It rotates between pornography, conspiracy, superhero and supernatural like a slot machine. It started off as this seemingly innocent story about two dominatrices having a rivalry in a fairly typical Porn with Plot fashion. Then they stop to talk about how drugging people against their will is bad, then there's magic powers at a public "spank-off" - it goes on like this. Cerebus Rollercoaster indeed. Apparently it plateaus later with less of the really nutty stuff, but you have to get that far without being thrown off first.
Second, it tries to do lots of different things and isn't fantastically good at any of them. A lot of porn falls into the trap where it relies heavily on the sex appeal and skimps on the art quality - something quite evident here. There's improvement across its run, certainly, but it still falls back on anime clichés like same-facing and flounder mouth, and even at it's best it's simply serviceable. If you were there for the plot, well that seems to dry up about halfway through.
Overall, interesting concept, mediocre but improving realisation. Not unusual for a webcomic, really.