Colbert just plays a character-- the over-zealous holier-than-thou Fox News type people Jon Stewart makes fun of every night at 11 or so. (He was equally funny a decade ago on Whose Line is it Anyway?)
Anyway... yeah. Back in February, I believe, immediately before the Olympics was the final The Tonight Show With Jay Leno, I was kinda sad to see him go because I watched him growing up (and hated the show after he came back, mostly because I liked Conan on Tonight), and after the Olympics ended, we had the first episode of The Tonight Show Starring Jimmy Fallon.
And it is awesome. Even if I can't quite remember how the new theme goes, I can still at least sing along with "Hey, hey hey hey!" (Yes, the theme song for The Tonight Show has lyrics now. It's a nice jazzy song, but what do you expect from The Roots?) Fallon is hilarious, and he took the time in his first monologue to actually acknowledge Conan O'Brian hosting back in 2009-2010, which the rest of NBC seems to have some kind of aversion to.
Sure, Jimmy Fallon still holds fast to Tonight's "Monologue > Second Comedy Act > First Guest > Some More of the First > Second Guest > Musical Act" formula, but in this case, "Some More of the First" is more than just an interview: Jimmy Fallon's a fun-loving guy, and he and his guest play a game, sometimes with the audience, they could do a comedy bit (such as History of Rap, Part 6 with Justin Timberlake on his second night), sometimes he gets Questlove from the Roots involved with the comedy, and all in all, I think Jimmy Fallon's doing a great job and is gonna be remembered as one of late night's best.
(The less said about Late Night With Seth Myers, though, the better. Ughhh.)