Been pretty good so far. At the moment I've found some of the large, 2x2 rooms to be not that fun. One of them just had the random moving worms in it, making it such a pain in the ass to get the last one.
I enjoy that it's being much nicer with the abilities early on, though I find too many rooms that have cool stuff in places your player just cannot get to. I assume you need a flight-based power to get to them. Was annoying in the first game too.
I like the new retro style, but I feel they went a bit far in the menus. Pixels writing does not really work when made on an angle, just makes things super hard to read.
Lastly, I think there could be a lot more feedback in the results screen of the game. Rogue Legacy has a really nice way of putting everything you've done on the screen, Binding of Isaac's is just kind of there.