I am not going to review the music - others have done it better, and at this point if you are looking at Hawkwind reviews you know what to expect. But I wasn't able to find any detailed info on this set, so I will give some details on what to expect from this for the fellow Hawkwind fan.
This set includes the complete first 4 studio albums each on seperate cds (1970 Hawkwind, 1971 In Search of Space, 1972 Doremi Fasol Latido, 1974 Hall of the Mountain Grill), each release is the 1996 remaster with the 2001 EMI copyright, and includes all the bonus tracks that you see listed for that (ie 11 tracks on Hawkwind (including the Floyd cover Cymbaline), 9 tracks on Space, 11 tracks on Doremi, 13 on Mountain Grill).
You do not get any CD booklets or proper jewel cases (just white cardboard sleeves with the album picture on the front and the track listing on the back), but for $3 a disc (or a quarter a song) you can't go wrong.
Update 2012-05-08:
When I wrote the review, the set cost $12 which is a steal. Since then, it is now over $25. You can buy the individual CDs new for ~$7 (with shipping) each, and then you get all the jewel cases + back cover art + a proper booklet in addition to all the music. The music is definitely worth the $25, but the artwork is probably worth another couple so you may want to spend a little bit more...