Pure awesome! Just enough good crunch to make people actually want to play it without it being a powergamer PrC. The only regret is that it's very bad for a caster. Maybe you could have the levels of sneak attack give your choice of +1d6 sneak attack OR +1 caster level, player's choice. With that change, I'd love to play a sorceror that goes into this in an average-power campaign. Also, I'd love to use this thing's abilities to screw with the Min/Maxers and powergamers I know.