I asked the same question a ways back. The general consensus that I disagree with was that no its not overpowered and no its not better than control undead 7th elvel version. Me I think it is too much for a 4th elvel spell and it is vastly better than the 7th level version. The 7th elvel version I think is a decent spell but no where enar as good as a 7th level spell should be.(its duration is feeble compared to every other control style spell and doesn't come close to making up for oh so powerful effect a lot of HD of creatures thing.) Compared independently of ther elvels yes, I'd agree that the 7th level spell is perhaps a little better, but 5 levels better not even close.
I made the 7th level spell a 5th level spell in my game, and the 2nd elvel spell a 4th level spell.
By the way if your a player and your DM allows the T&B version, think extend spell, and think chain spell. This is about the one and only way you can control armies of undead. Since it effects one creature an ignores HD, go for the big bad mindless undeads. Make an army of ogre, giants, troll skeltons arm and armor them and have some fun. If your the DM Bwahhahaha.
