Lucas has a rainforest play gym by Fisher Price...and it continues to be pretty awesome. This gym has lights and music in addition to the hanging toys and colorful playmat. He has loved his gym since the first time we put him in it. As a parent it can be a little overwhelming deciphering what "developmental" toys to invest in, especially when you know how important playing is (without underlying development pushing). Actually, there is a ton of research about the benefits of child-led play and the need to foster imagination. In fact, there is a huge stink about how recent federal mandates about education accountability has had a direct and negative impact on kids in grade school who no longer get recess. Bottom line - Play is important and child-led play is even more important! I have taken a few play therapy courses and simple toys can help children express themselves so much more than a toy that is linked with a character. So...I guess what I am trying to say is that I carefully evaluate every toy that comes into my home for multiple reasons.
The Fisher Price rainforest gym is great because as Lucas's perspective changes, he explores the rainforest and finds new things. At first he would just lie on his back and look at the lights and hanging toys...then he began reaching for the toys (which I am able to move around, add and subtract, etc)...next he began kicking the toys and arches to make everything move (and the music continue)...Now he will be on his tummy and playing/talking to the fish and animals on the mat...and he sits in the rainforest and tries to mouth the hanging toys. I like that the gym has continued to delight him into his 6 month!
I don't necessarily think this is the be all end all of gyms - there are countless other versions out there by different companies that I have not even seen in person. When choosing a gym for your baby, I would recommend laying down and sticking your head where his/her head will be and decide if it something that sparks your imagination. If it plays music - listen to the music and decide if you like it (because trust me you will soon have this little ditty memorized). Explore the different options you have with the gym, can you add other hanging toys or move the ones in it around?