I used to have their XM3 after Rocketjumpninjas recommendation and I thought it felt cheap overall, the buttons were really lacklustre and the shape didn't suit my hand anyways.
But looking at the M2 it looks a lot like the Logitech G203 which is a great mouse for the price, I got one for £15 and just have it as a spare just in case, so personally I'd probably get the G203 over it and not risk it.