The system isn't really that hard, once you get the hang of things. I mean seriously, compared to something like Hero System, Shadowrun is a breeze to pick up.
I don't think the problem of games dying is a problem with the system. The half-life of PBP games in general, regardless of system (or lack thereof) is about 2 months from creation. Just the way things go. I've seen D&D 4e games that died before the first combat, and I've seen a D&D 3.5 game that lasted over a year.q