Does anyone else think these guys look like poorly-designed aliens?
Bodaks have nine undead RHD. That is bad, because it means giving up five BAB or nine levels of casting. The immunities it gives them are nice, but if someone wanted those they could just be a necropolitian.
The bodak's chassis isn't great. Low ability scores, a few energy immunities, and a poor natural weapon. The DR is decent.
And then there's their gaze attack, which is surprisingly useful. Monsters with immunity to Death are much rarer than PC's with immunity to Death, meaning you can essentially force one SoD a round.
But is this really special at that level? Remember, a 10th-level favored soul with Versatile Spellcaster can easily throw around six Slay Livings a day, and the favored soul has other abilities too. The bodak may be able to target multiple people a turn, but the main way of protecting allies from your gaze (Narrowed Gaze) makes that tactic impossible.
And let's not forget that the bodak has little to no advancement options. Spellcasting is out, so are most forms of melee, and little material actively empowers your gaze. Most likely, you'll have a bodak and his class levels with no synergy in between.
Final LA: +0.