Oh, yes. With those things, it is very much playable, to the point of almost mage-like power.
Dispel with no check, 2/round, almost at-will.
Slow with no check, almost at-will.
Fly, almost at-will.
Daze (save or daze), 2/round, almost at-will.
Repair Magic Items, almost at-will (use this with Magic Tiles or other "used and destroyed" magic items)
Restore Dispelled Magic, almost at-will...
Done right, it's more than useful. A full caster may well be stronger, but it's far from a Monk. Well made, I'd put it above a Warmage or a Warlock.
For a DM, it's easier to manage than a spellcaster without throwing things specifically built to counter you.
That said, without a LOT of boosting for your Truenaming, it simply fails to work reliably, and as such, fails.
A level 10 Truenamer should be around this value:
Truespeak: 50 + INT (13 Ranks + 13 Item Familiar + 10 Amulet + 10 Affiliation + 2 Racial (Illumian) + 2 Tool + INT)