Good as the first, better than Bond I just saw a private screening of SK2 (okay, I was the only one in the matinee at this late date) and loved it. I find it easily comparable to the first - most people will love or hate both, unless you liked it once but don't want more of the same. As a kid, I'm sure this would have been among my favourite movies. As an adult, I'm surprised that I liked this at least as much as the latest Bond - in SK, the super-science is expected to be fantastical/over the top, while Bond's should have some basis in reality but doesn't anymore.
Fun gadgets, realistic character interaction (siblings, in-laws/grandparents, first crush, co-workers), big-names in great supporting roles and cameos, and best of all, a skeletal swordsmen scene right from Jason & the Argonauts - I haven't been in heaven like that since the Mummy! The LotR references were great, too, along with lots of other good ideas mined from classics and more recent films. I don't mind when a movie steals elements from other films as long as it does them right, which this one does.
Some people have complained about the gross-out humour, but there's not really that much, and it's totally in line with standard joke-fodder for kids that age, so if you can't accept that, you don't know kids. In fact, I thought the camel-stains showed better continuity than featured in most adult films, as it remained but was never mentioned.
I'm sure kids will love it, and adults still in touch with their "inner kids" will, too. Be sure to stay right to the end of the credits for all the great extras!