I've tried them. They're pretty much like you'd expect. If you hang large, or if you tend to show a bulge in other (read: regular fit) jeans, then you're really going to show off in the skinny ones. In a lot of situations, and especially for a lot of bigger guys on here, they're not going to be appropriate. They're not for everybody, and I think that's part of the appeal for some.
That said, if you can pull them off with your body type, and you're planning on going out to pick up girls/guys, and you want them to know you're packing, throw them on, and you're likely to get your message across.