I just got back from a visit to Legoland with my 6-YO son & it was FANTASTIC! I see lots of people dissing the park but it gets my vote! My son was allowed to choose where we went for vacation this year & that's where he wanted to go.
I LOVED seeing all the things built from Legos, he loved the rides & activities. He's used to going to Astroworld here in Houston, where he's not tall enough to ride a lot of the rides. He could have ridden everything in Legoland if he'd wanted to (he doesn't 'do' rollercoasters!). We rode the Hydroblaster (I believe that's the name) FIVE times!! None of the lines were long, except for the self-propelled water boats. He LOVED driving & getting his driver's license there. We spent all day & were disappointed when they closed. We had to be 'shooed' out of the park at 6:30 (they closed at 6 the day we went) & could've stayed MUCH longer.
When I asked him what his favorite thing was in the Park he really surprised me & said "all the things made out of Legos". I expected him to say "Hydroblaster" or one of the other rides but he (& I!) were just fascinated by the Lego sculptures/animals.
I agree preteens & teenagers would be bored there, unless they REALLY like to build things w/Legos. But it gets my vote as a terrific park for kids!