The cool thing about M-S recording is the two microphones involved do not have to be identical as per many other stereo recording techniques.
The other great thing about MS is that the Mid microphone is pointing directly at the source, something that does not occur in other stereo mic techniques. Because of that you get a very nice direct on axis sound.
It is a very under rated technique and of course the ability to manipulate the stereo image after is very cool. Matched microphones are also a good thing even for MS. The M microphone can be cardioid but can also be Omni for a nice room effect.
MS is also easy to decode in Sonar as well without the hassle of duplicating S tracks and panning and phase reversing one of the S tracks. 3 Tracks in total.
Mono compatibility is also very good with MS.