I am not sure about any known problems, but from the times I've been in one I really like them.
The interior is cavernous. Unless you are over 7' your legs won't come close to the front seats when sitting in the back. The second row also reclines (although I think this is an option).
They are really quiet and with the standard 6 in there, should deliver low to mid 20's on the highway.
Also, the nav and sync are pretty slick and work really well.