Well I've worked with two Iranian men, and I assume they were muslims. One of them was great to work with in every way and a really fine gentleman. The other guy was very congenial but he had a problem with honesty and tended to not do what he told his co-workers he would do. I think the assimilation issue probably has more to do with education level and the extent to which muslims believe in western economic principles and values. These two men appeared to be well-assimilated into the US workforce, if not at a social level.
You know how when you take a test in school they say never pick answers that involve "Always" and "Never"? It's true with most things, including stmts against races, religions, etc. I do't doubt there are many good Muslims in the world and here in America. It just takes a handful of people to mess things up.