I have mostly spent my Doom playing time this month in Plutonia 2, the unofficial sequel to the Final Doom megawad. I took ages getting round to this, obviously. When it came out I hadn't played the original yet, so I did that first. It's also not without its bugs, so I think another reason might have been that I was waiting for a re-release. Not sure though.
Is it better than the original? Yes, I think so. Mostly because half of the maps are by Gusta, who did most of Kama Sutra and knows how to make a proper well-connected layout that's not full of annoyances and disjointness. But the rest of it is authored by People Who Know How To Map as well, so...
Is it buggy? Well, sort of, although I can't recall any real showstoppers off the top of my head. Maybe a few monster teleporters that don't work properly and some visual errors. There's a little lack of polish, I guess.
The final boss, even if it is just another variation on the theme of "the thing that sits there and spits monster cubes at you", is very clever and worth seeing (although could just be seen as a refinement of TVR map30, with which it shares an author)
It has more than 32 maps, like Claustrophobia 1024, Whispers of Satan and a couple of other modern megawads. I am not a great fan of this practice.
Very good, though. One of the best? Probably, I'll have to play it a bit more to be sure, but it's definitely up there with KSutra, HR, AV, etc.