1. SCV's mine 5% faster
2. Gain an observer unit equal to protoss, except it is undetectable and indestructible, although it does not allow the targeting of invisible/burrowed creatures.
3. Gain a 20 supply increase to your max (max at 220)
4. After gathering 200 gas, you receive all first level, unit engineering bay and armory upgrades for free (buildings still required and normal research time)
5. Receive 3 free SCV's at 6:30, all appearing right next to your mineral line in your main
6. You receive a new 'split' command for your marines only, they will split into groups of two
just far enough away from each other to avoid the baneling splash damage radius.