I rather like it, though I have only run a game od it once.
The rules for damage are very interesting, and make combat a great deal less predictable than standard D20 - nearly any good blow has a chance of taking a hero out of action. As a result only one character actually engaged in combat at all, and she was an ogre. (And sure enough, one blow took someone down, fortunately not the PC.) It also gets rid of the tendency for higher level characters to hold on for that last battle - without Hit Points to use as a guide it is a lot harder to figure that you can survive fighting that last minion or villain.
Conviction is also a good mechanic, giving actions moral consequences, somewhat similar to Taint in Oriental Adventures comined with the Force in Star Wars. (Though somewhat lower in power).
Over all I feel that it is a good game, and looks very easy to modify to fit your needs. The only reason that I have not used it much is that I so very much like Spycraft 2.0. (Combat in True 20 was not bad, but the first combat I ran for Spycraft had people standing up at the table and yelling what they were going to do. It was a complete blast.
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The Auld Grump