I didn't really like him at first, but he's grown on me.
However, I've noticed many times how enemies will walk right past him for about 3-4 seconds without him doing anything at all. I mean, I understand the whole minimum range deal, especially with throwing axes and spears, but his attack is the same(at least in appearance) and his minimum range seems really large. If he would go and engage the enemy it'd be fine, but he just site there while the enemy walks by.
Oh, and does his tower boost increase with level?