I've mentioned my enjoyment of the character several times, but he isn't exactly deep, and it's hard to have a character like that as the central figure of an episode without it wearing a little thing. He kind of reminds me of Chief Wiggum from The Simpsons, who is almost always excellent dropping in for a line, but you don't want a whole lot more than that.
Lewis's limitations are fairly apparent in this episode, which takes a moderately interesting premise – Stan helps him get married so Stan can be the Best Man and live his dream – and fulfills it moderately well. Lewis's psychosis is on display multiple times in the best parts of the episode, as he either gives in to it totally or fights it when trying to be a better man. The dog-punching thing is a good example of the MacFarlane brand of weird/shock humor working. Stan's fervent desire to be a Best Man is also quite good, and while it's a bit out of nowhere, it's fits nicely with his personality generally.
The problems come from elsewhere. The B-plot, involving Roger finding a magical pair of shorts and hooking up with Ricky Martin in Miami, goes nowhere. There's a self-referential gag about the comparative realism of American Dad and Family Guy, a couple gay jokes, and a few cute little montages showing how good Roger looks. I guess the fact that it was actually Ricky Martin saying "But Roger, it's time for butt play!" makes it a little bit funnier, but the whole thing generally felt more Family Guy-style "funny" than the more natural American Dad form.
The bulk of the story involved Lewis's relationship with his former prison cell-mate, Tracy. There seems to be a general rule of comedy that prison rape is inherently funny, and while American Dad doesn't quite go so far as to say that the prison sex Brian and Tracy engaged in was rape, the whole concept of "prison wife" and distribution of "bitches" are built on that foundation. But hey, I wouldn't be reviewing any MacFarlane show if I had such a thin skin as to say that Lewis having a prison wife would never be funny. But the episode never really does anything to change my mind. Tracy is funniest when he's more separated from the prison wife conceit and the show combines his semi-gangsta persona with his domestic urges. Stan supposedly drags him away to Brian's house and he yells "First thing I'm gonna do is plant some heirloom tomatoes up in here!"
So while certainly not a terrible episode of American Dad, I'd have to say this is something of a missed opportunity on multiple levels. Prison rape, gorgeous Roger, overly gay Ricky Martin, Diff'rent Strokes references and Anjelica Huston just didn't add up to a coherent whole.