Are you talking about visuals only or gameplay as well?
Pretty much visuals only. Gameplay, as I said, is now sort of dull in Doom 1.
Personally, I've never been that impressed with E1. Sure, the shareware version was innovative for its time, but honestly, it didn't do it for me. I liked it but it was lacking something, maybe it was too easy, too empty or whatever... I've always preferred E2 which isn't flawless either. E3 was clearly half-assed (that's even an understatement with regard to E3M9), and it looks really bad in places.
Well I played all that stuff on the SNES at first and it's nostalgia in the most part, honestly. I can see how Inferno is half-assed in places, but it never bothered me to the same extent as many Doom 2's levels. Sure I got around to Doom 2 considerably later than Doom 1 but it was still a long time ago, almost half my life ago. Doom 1 still seems much cleaner and more polished than Doom 2 in that regard. Plus, hey, Doom 2 had some very questionable gameplay choices as well, like that shootable door thing in map28, which is completely inexcusable.
I've seen many people complaining about Tricks and Traps or Barrels o' Fun who turn a blind eye to maps like E2M9 or E3M9 at the same time... Hell, the barrel jump from map23 is so staggering that even watching it is worthwhile. Sure, not all Doom 2 maps are aesthetically pleasing (and neither are a lot of those from Doom 1), but they're still a lot of fun to play.
Part of it is the names. E2M9 was always an oddity to me but since it was a secret map I didn't care, I just viewed it as a way to get a lot of ammo and a health boost. E3M9 is harder to defend but it's gimmick was really surprising and awesome back when I was getting my first impressions. But even Warrens doesn't come any close to the total disregard for any kind of setting or, I dunno, thematic consistency with names like "tricks and traps" and "barrels of fun". To be completely honest, if those names were more like normal serious level names and not that, I'd have much less problems with them. Maybe almost no problems at all, even! But level names are such a useless thing to many people that I see how some can find nothing offensive about those two maps. Heck, a lot of people give their maps stupid-ass names all the time, like song titles or something that has nothing to do with what sets the particular map apart from others, like some abstract idea that has to do with pain or suffering or death that could be a name for any and every single doom map in existence. Yeah I really care about the map names :3