Its not too powerful when you consider thats all rogues really get. They get good skills sure, but bad hps and average combat ability usually means they need sneak attacks to be worth anything at higher levels other than opening doors and chests.
I'm glad rogues one of the better classes these days. I remeber when making a pure thief made people laugh. At level 20 you couldn't do anything worth noting (save on that day once a year when you got to backstab something and do good for a round).
Rogues are deadly if they flank you. If not, they are toast against any other class one-on-one.