I'm an admitted music snob in my 30's, who was weaned on the early/mid 90's hip hop scene that I still think is the pinnacle of the genre.
I think lil Wayne is a genius.
He's never going to be realistically compared as a lyricist to people like Nas, Kweli, etc. He is a great punch-liner with a deep arsenal of (mostly sports and pop culture) metaphors, however.
Most importantly, though, he's a brilliant, and incredibly unique, pop star, the weirdest artist to succeed in the mainstream since Ol' Dirty Edited for profanity. Please do not do it again. was selling "Return to the 36..." to 14-year-old girls who lived in trailer parks and mostly listened to country. "A Milli" was a top-40 radio hit for god's sake, and that's on the short list of the strangest songs I've ever heard on the radio, popular, underground, or otherwise.
Based on everything I've read about his creative process, I'm also convinced that it's conscious, and intentional. He's not just getting wasted and mumbling things into the mic; he records his vocal tracks over and over and over, to make sure that every phrasing and intonation is exactly how he wants it to be.
He's also doing a lot of things that are generally considered "lazy" or looked down upon, rhyming words with themselves, using "middle school level" potty-humor, etc. But he makes it sound great, and I think he's doing it very self-consciously, playing off of the "Li'l" moniker, and the fact that he was making gold records when he was 14.
This is an incredibly smart guy, one of the first relatively self-made platinum successes from the post-napster, give-it-away-for-free-on-the internet era of the music industry, who's pumping out huge numbers of songs, all of which are consistently solid, and usually better than that.
I also think that's it's pretty clear that some of the biggest names in the industry admire him, and think he's going to be at the top of the game for a long time; he's getting Jay-Z as a guest on his album, landing guest spots with kings of hip-hop pop OutKast (other than Raekwon, Snoop, and Ludacris, he's the only non-Dungeon Family guest I can think of to get a verse on a any Outkast project) and getting beats from the likes of Kanye, Alchemist, and David Banner (who I don't get, personally, but who produced a track for freaking Rza on the new Bobby Digital, and Rza's still an unassailable taste-maker, IMO).
I certainly understand why people don't like him, don't get the shtick, only care about "real" hip-hop and not anything that leans more toward pop, etc.(Do the anti-Wanye people like OutKast? I'm honestly curious, because I think he has a lot in common with them as pop stars.) But he's too well regarded by too many top hip-hop taste-makers, critics, and a sheer mass of fans to dismiss.