I think the major difference in this year's challenge was that there was a larger number of missions that were relatively easier to solve. So while each individual mission was, on average, easier to solve than last year's, it was harder to get many of them done in the time limit. Apparently the challenge was made such that a perfect score would be very rare (the designer, Scott Evans, said he considered that if a team got a perfect score, they "beat" him, because he tried to make it really hard to get one), but it may well have turned out to be easier than last year.
One of the new aspects of the teams this year is the amount of NXT robots vs. RCX robots being used. Out of about 60 teams I saw in NJ, I only noticed a few that used RCX robots. This is interesting since the fairness bonus for using an RCX is quite a bit better than last year's. The NXT is definitely catching on in the FLL community.
Though I haven't been to an official tournament, a scrimmage practice with 10 teams I recently attended had all NXT robots! And since most of these teams were new, I think the NXT is really causing people to start up teams.
I think this is one reason Scott Evans might have made it easier than claimed; he guessed that the release of the NXT would start many new teams, so making slightly simpler missions would make these new teams' first year smoother, while the complexity of other missions would still give (somewhat) a challenge to older teams.
And even though teams are scoring higher, I've noticed that robots are no longer as technical (? correct word?); many rely on dead-reckoning (even though teams like Jonathan's shows that this works just as well) and no longer use many or any sensors at all. In the days of the RCX, teams had to rely on sensors to get any accuracy at all. I think this is one area that the NXT can improve in.
So good luck to everyone, and I hope to see some of you at the World Festival in Atlanta!
-Jonathan and Richard