Stronger, faster spark. Multiple Spark Discharge (MSD) fires three strong sparks instead of one at lower rpm's, can fire better than standard points at higher rpms (>8000). Easier motor startup and all kinds of add-ons for various functions (multiple rev limiters, timing retards, etc for various applications like blower/nitrous/racing, etc).

I'm glad I switched, but I did have a magnetic pickup go bad in my MSD distributor after only a few months.... they sent me replacement pickup for free (but I bought another one at ~$20 to have on hand for a spare).