I haven't used it, but I've seen a bunch of presentations and I talked with the developers who built LINQ last year.

They realize they're in a 1.0 release, but they've tried to structure the SQL statements they submit to perform well. Lots of workloads from different applications were used to model what they do and for many of the queries, relatively few (inner) joins, their SQL performs well.

I think it can be good or bad, and you should proceed carefully. Run some small pilots, build things two ways, see which one might work better.