As I've mentioned before, it does, in several ways. For one, it slows down my hyperactive mind to some degree, not in the sense of making me feel stupid, but it reduces the emotional "need" to let each train of thought bloom into a magnificent tree with a life of its own. This makes it easier to pause the internal monologue enough to follow something like a conversation. In fact, this benefit is also one of the biggest drawbacks of the drug for me. While I can feel some sort of mood lift, in some sense I almost can't feel true, deep excitement while high, because of that slowdown.
Also, it allows me to get more in touch with my senses, and with the world as unfiltered by my assumptions. I know some aspies are more hyper-sensory and some more hypo-sensory, and I'm much more the latter--my attention is like a pinhole camera that only lets a few things in. When high, I notice more of the raw data coming in, as opposed to a small amount of data with a complex inner world built around it.
And yes, the relaxation is much more unpredictable than with alcohol, in fact weed can cause panic sometimes, depending on strain and especially on my state of health. Alcohol reduces the feeling of being out of place socially, but because it actually makes me more comfortable in myself, it doesn't actually help me connect.