I recommend listening to T-Pain's rEVOLVEr (or RevolveR or whatever asinine capitalization he ended up using) the same day as The Beatles' Revolver to get a good idea of just how unremarkable Pain's fourth album is, but listening to either of his first two albums, Rappa Ternt Sanga and Epiphany, would provide a suitable contrast too. Although my opinion of the guy never totally lined up with popular opinion (I always thought he was more talented as a songwriter and producer than just a guy who caught a lucky break with the AutoTune gimmick, and prefer a lot of his deep cuts to some of his biggest hits), but my decreasing interest in his music coincided with his commercial decline; his last couple albums sold 170 thousand the first week each, while rEVOLVEr only did about 34k. It's possible that T-Pain was never as famous as I thought he was; my wife, who's not a big R&B buff, saw the video for Flo Rida's "Low" today and said "who's the guy singing the chorus who sounds kind of like Nelly?"
T-Pain's flagging career was actually what revived my interest in his music, since I ended up writing a whole column about the six singles he released in advance of rEVOLVEr before one became a big enough hit to get the album a release date, and felt more curious to hear the album after that than I might've otherwise been. And while I wouldn't rate "5 O'Clock" up with the best songs of his peak period, it has turned out to be his biggest hit in years and, unfortunately, easily one of the best songs on a fairly uninspired album.
There are some decent songs on rEVOLVEr; "Default Picture" is one of the best slow jams T-Pain has constructed to date, and there's something kind of enjoyably surreal about a love song written to someone's Twitter avatar (especiall since since the person that wrote it is my Twitter avatar, kind of). But there's a lot of really bland stuff on here, even compared to Thr33 Ringz, which was a step down from his first two albums in quality anyway. The biggest disappointment, though, is that I was always an especially big fan of Nappy Boy Productions, and here T-Pain only did the beats for 5 songs, after producing every track on his first three albums, without any of the outside producers on rEVOLVEr doing much to help the album's quality or variety.