So I played the Backer Demo this weekend. First time playing the game for myself, so I can't compare to the Beta. It has quirks, but for the most part, I liked it. The controls were more responsive than I expected, and the dashing actually felt pretty good. I'll admit the gameplay looked kinda monotonous in some videos, but I find it's a lot more interesting to play than it is to watch. The new voices add a bit to the overall presentation too.
The most frequent thought that came to my mind while playing, was that the game feels less "Mega Man" than Shovel Knight, and more "Sonic" than Freedom Planet. It's very arcadey compared to traditional MM, and like Mcpeanuts said earlier in this thread, it puts a huge emphasis on scoring and speed. The stages and enemy placement make a lot of sense when you play fast, but if you play cautiously without caring about score, the game will feel fairly simple and straightforward. I'm curious to see how this approach pans out for the rest of the game.
The only things that really bug me about the game right now are some aesthetic decisions. Currently, in its (supposedly) close to finished state, it looks like the game just doesn't have the same little details and character touches that you're used to seeing in other indie titles, such as Shovel Knight. Backgrounds feel surprisingly lifeless, even the hub-lab where the characters reside, and I think the cutscenes could have been served a lot better as 2D splash art (ala X5/X6), rather than just seeing the same 3D characters standing around with their mouths hanging open. There are also some stage obstacles that are handled rather lazily, like big explosions that lack impact, falling objects that blatantly clip through the floor without any effort to disguise it, and other rough spots. The overall quality of the graphics don't bother me at all, but I think the lack of those little details are what make the game feel a bit budgeted right now.
Overall, I think I'll be having a good amount of fun with the finished game when it finally comes out. Its playstyle is probably not going to satisfy a lot of MM fans, but thanfkully, there'll be plenty of other cool platformers out there for them to play as well.