I just got my Nillkin from ebay last night, barely used it, so here's my 30 second review:

Quality feels nice, not cheap - no idea how it'll hold up too abuse yet, but so far it seems quite good for the price.

Very slim, definitely more trim than the MoKo (have that too). The clip covers basically the entire edge on either side of the front bezel, not much, but you still notice when swiping to the edge of the screen.

Smart cover is cool, wakes up screen and is thin (the nexus feels like a nice book with the cover closed). It does not stay folded back on it's own; can be folded up into a landscape orientation stand, but it's not as sturdy as the MoKo type covers.

Tablet holds nicely in your hand like a book with an open cover, but it's not ideal for use with a portrait orientation stand (a la the Nest) - it can work, but I prefer naked.

Great for transporting your nexus within a laptop bag or similar - screen will be protected from scratches, but don't expect drop/shock protection.

Edit: purchased 11/30/12, estimated arrival 12/20/12 - 01/09/13, arrived 12/10/12 (free shipping)