I have seen a lot of people say that the Truenamer does not work (such as this answer placing Truenamer at the bottom tierthis answer placing Truenamer at the bottom tier) or that it's terrible.
As far as I can read and see, though, it seems to be very strong as a caster type. At low levels it doesn't much more or less then a low level wizard, but at higher levels it becomes quite strong. The Truenamer has the power to alter reality and bend the rules of time in a single round with a skill check that can be modified heavily in his favor of DC 15 + 2xHD or CR of target. At level 1 you have +7 to your True speak check and your DC for a CR 1 or Ally is 17.
I don't see the problem. So what's wrong with it in detail?