I'm an avid Epilogues and HS^2/HSBC fan, so I'd be happy to share some of the points I genuinely enjoy. Sorry if it's all a bit ramble-y.

First off and at the most basic level, its of course just More Homestuck, so it'd have to be really bad for me not to appreciate it at least a little. But I also don't think it actually is bad on the whole of it, even if it takes some things in directions I don't "like" to see. As much as I love the cast of characters and want to see them finally be happy and fulfilled, that itself doesn't make for a properly sensational basis for telling a compelling continuation of the story. So thrusting them back into the narrative limelight is going to entail robbing them of their "happy endings" such as they were. And the Epilogues aren't shy about deliberately undermining any sense of closure for p much the entire cast.

Besides, where Homestuck proper leaves off at the end of Act 7 there are still plenty of plot threads still up in the air. Getting off the ride that is Homestuck at this point was always going to mean accepting not being able to tie those up. The approach the Epilogues and Beyond take allows for as comfortable an off-ramp as you're likely to get for anybody whose truly done with Homestuck, while still providing various branching points from which to continue things in all sorts of directions for those who are still interested. Effectively getting to have it's cake and eat it too, which is both very Homestuck, and one of great things about fiction in general.

As for the characterizations, they all basically work for me too. None of them strike me as particularly out of character, just as disappointing turns for them to go down. The roads to self improvement they were beginning to go down are unfortunately rarely linear journeys even for well-adjusted people, which these characters definitely aren't. Relapse along the way is normal, and even to be expected, especially for a gaggle of child gods with a severe lack of support systems and accountability in the new world they've created. Plus, just seeing how things fall apart is interesting to me in itself.