Yeah, I like Tehenhauin.
He's our cheapest Lord choice and he fills two spots. If you're really looking for a caster Lord without dedicating yourself to the slann set up he checks that box. Lore of beast is pretty cool too with some of the best spells and he gives hatred to all your skinks when fighting skaven! It really makes those skrox units much more powerful and your skirmishers too (and stegadons and terradons etc).
The second slot he fills is the EotG if you want to take one. First you say "Wait, he costs 540 points with the stegadon making him more than an oldblood on carnosaur!" But he fills two roles in your army, and gives you that variety from the normal Lore of Heavens skinks priest. The only other place you'll find a Lord + Stegadon is Mazdamundi... which, interestingly enough, is only 80 points more for a level 4 wizard (who Tehenhauin is actually better in combat than)...
I guess it just comes down to personal choice.
If you're looking for a break from "hero hammer" this guy is it. He is pretty strong in his own right but his power really comes from what he does for your army. I'm a big fan of generals who make your army stronger rather than replacing it on the front lines. But, that's just me.