I'm not a Muslim (although I accept certain aspects of it at this point in a syncretic manner) but what I have seen (as it'd be plainly obvious) is that there is a large schism, and large amount of splintered groups, sort of as you'd find in Christianity in particular.
When that's the case (as with many religions) it's always a double-edged sword. In some aspects it's good to have sub-areas, but it also creates a greater sense of division, which isn't positive.
Often I see it as ideological differences that separate denominations and the such, but sometimes it is nitpicking the religious practice aspect. While I'm no expert on Islam, I definitely see this as one of the bigger issues within the religion.
