It is a very good sequel, dont worry. It has the same humor, even more interactive environments, more mini games, it even has physics puzzles. Because of the variety, the guns and the puzzles and the fps view story telling, it feels very much like Half Life 2. So if you prefer a more interesting and varying game like HL2 over simple shooters like COD MW, then the Duke is the perfect and the right game for you.

Actually I enjoy this game a lot and many other people enjoy it. But a lot of COD kids hate it, really, they write very emotional posts against it. I wonder why. Also I think that the hype created some people with high expectations and they might also be haters now. I dont understand why, I personally never believed that it will become the next generation of games. From my experience with bad sequels I expected another bad sequel. But I was positively surprised that this game feels a lot like the old one but better looking, more content, more gameplay mechanics, more variety.

It also is not perfect. Modern shooter guys have problems with the old-school design and old-school fans dont understand why it has automatic healing and a restriction of 2 weapons at the same time. Levels are also a bit more linear than in the old days.

But really, if you read these passionate hater blogs and reviews, then it sounds to me, that they fell into some hype and are now disappointed that the game indeed is "only" a better Duke Nukem, just a remake of the original game, the same good old story, the same fun. I really enjoy it, honestly.
And below each of these blogs and reviews you will find people who agree and people who disagree and many people who enjoyed the game. Probably this kind of macho humour really is not for the current kind of casual gamer mass.