Right off I will say I got this for free. Playschool gave a few of these away to Babycenter forum Hosts. My daughter was at the top of the age range (6-18 months) but I signed up for it anyway. It came right before Christmas so we saved it as a gift for our daughter. She received it today. We set it up on Christmas Eve so it was ready to go this morning. Believe it or not, she passed every other gift to play with the Discovery Dome first. And she hasn't stopped playing with it all day long. This is one of the coolest toys out there. She plays in it like a fort, crawling in and out through the door, dropping balls down the chute, playing the doorbell. Her favorite toys and books are already stashed inside. If I had an infant again, this would be my first toy of choice above any of the other infant gyms (like Baby Einstein which we had for her when she was younger). This one has so many things to do and it really grows with the child. And the price for what you get is awesome.
The Discovery Dome was easy to put together (very little assembly required) and is good and sturdy. I love that it can collapse down very simply and has two velcro tabs to secure it while it's collapsed. It has lots of fabric loops for hanging toys. The toys that it comes with are perfect for younger children. Most are a little young for my daughter (who is 18 months) but the doorway, doorbell, dome itself, etc are just perfect as an older baby's private space.
UPDATE: December 28. 2007. I thought I'd add an update. We've now had this toy for a year and my daughter is 2 1/2 years old. She still loves this. We call it her "tent" and it's a permanent fixture in her bedroom. For a long while she slept in it, now she just plays in it and loves to jump over the door and land inside.