Great toy!  My 5 year old son got this for Christmas this year and it's been a big hit.  He loves playing with it.  There are so many ways to configure this thing and it's easy for him to figure out.  Almost every time he plays with it he discovers a new way to put it together or a new feature on it. 

There is even a cool little "alien UFO" with a green alien in it with suction cups and everything.  It does have a sound button, but it took him a while to discover it.  :) 

This toy is surprisingly durable and I am continually amazed at the imaginative play that it has inspired.  It has been a big hit with playdates too.

There are other MegaRig sets that I will look into as well.  I think they have a submarine set, and a shark adventure set - but this space one really worked out well.