I always loved Leno doing the tonight show, he had a sense of humor that appealed to me. Of course, his style's rather disneyfied, trying hard not to offend ANYbody etc, but he was still funny as hell IMO and I was sad to hear he was going to retire, as it was reported where I live. Then I learned he wasn't gonna retire at all, but get another show and whatnot, but that's kind of a sidetrack really...
Conan's a damn funny guy too, and I can't help thinking NBC are a bunch of fricken maroons to panic over ratings only a few months after the show changed hands. Leno did the tonight show for what... 20 fricken years? Of course it takes time for people to adjust, and for the show to settle in a smooth groove.
I haven't actually watched the show with Conan at the helm, because it's a cable channel that has broadcasting rights around here nowadays, and I don't have cable anymore since I watch so little TV. Pretty much just the evening news, and that's it.