Letterman is still awesome. Conan is a little less awesome now that he's out west and has to tone it down a little bit for the earlier time slot. Craig Ferguson is still pretty funny; Kimmel is a douche; and Jimmy Fallon couldn't be funny if his life depended on it.
So nah, late night shows don't suck. But Leno is pretty unfunny for the most part and from what I've heard about his new format coupled with the earlier time slot, there's a high likelihood that he will be even LESS funny.