Major Tom is not your ordinary compressor. It was designed with very specific goals in mind, and blew completely past them.
Major Tom is intended to be easy to use: there are no attack and release controls the values vary depending on the level of the signal relative to its threshold. These values are very finely tuned to make it as musical as possible, without requiring a wall full of gold records to hit the right settings. The attack/release settings are inspired by one of the true stealth vintage compressors, the dbx* 160. You may not hear about it much, but you've heard it on records time and time again.
Musicality: That's the second key. Major Tom WILL pump, but it should do so in a musical, rhythmic manner. Those looking for utterly transparent gain reduction need not apply.