I've been using my surface on an almost daily basis for about a year now (I bought it when it was released).
The type cover still looks like new. I'd say I use it quite heavily, I'm a programmer and use the surface for a lot of my work.
The only thing I noticed is that the keys on the right hand side now seem to sit a bit deeper now, as in, they're not level with the edge anymore. Having said that, you can hardly see it and not feel it at all while typing.
That's the only wear and tear I've seen with it though, it's a sturdy little bastard, I've used it in all sorts of places from outdoors to planes and various other places.
The only thing that's about to give up on me is the charger. The cable didn't survive the daily packing / unpacking so I had to replace it... (stupidly expensive that charger)