It doesn't get too crowded per se. If you get there when the "gate" opens you can grab a fastpass and ride the googy's rollercoaster before the "presentation" starts. That takes about 10 minutes of seeing the main characters dance and sing. You all get an honorary citizen button. Then I would rush over to MIckey's house to get a photo op and autograph before it gets crowded. Then go through Minnie's house, Donald's Boat, the bounce house if you have really little ones, chip and dales treehouse. Then you can ride Roger Rabbit and play with a few of the cool extras around the "jail" and "post office".
Many folks here will say it's boring. But for my family, we love it. You can cruise around TT without big crowds and take cool pics. Our DD is 7 and she still loves it after 4 other times!
ballarinamom -- sounds like you are the first one to have posted about an enjoyable time at MTTMM. Just wondering how you got to TT so quickly at opening? Did you line up early and just walk through or did you take the railroad?