Exactly what my 4 year old son wanted.  We got it for Halloween but he has had a fantastic time dressing up in it and pretending to be an astronaut.  It has facilitated his learning about space travel, our solar system, and different jobs.

Update 11/06/2013 - We have had this suit for several years now.  My son is 7 and has come close to outgrowing it but his younger sisters are starting to put it to good use!  My 5 year old daughter wore it for Halloween this year.  It was a little big but still worked great.  It has been in our dress-up box and has been wore over and over again.  The quality is just fantastic and still looks as good today as it did when we bought it 3 years ago.