I've been on effexor xr for years, and recently added abilify. I've been diagnosed with major depression and generalized anxiety, but I think I have bipolar II due to episodes of hypomania. Anyway, I haven't been on abilify very long (a month or so), but I have not noticed any side effects. Possibly excitability, but I am not sure. I switched my dose from the prescribed qhs to qam. Seems to have helped with me winding down to sleep bc my sleep got really screwed right after adding abilify at bedtime. I have noticed a difference in how good I feel, it's nothing drastic, but I didn't need anything drastic, just a tiny boost. I think there may be some withdrawal though, if I don't take it soon enough. I have gained weight, bu I attributed it to not wearing my CPAP for sleep apnea at night for a few weeks. I will keep an eye on it. So far, so good.
I took abilify for a month and it really helped me without any problems! No side effects! I don't know anything about effexor, neither for the mix of both. You should see how you feel with it! I couldn't take lithium 'cause i had tremors and didn't feel well in general with it.
I hope for you that it will work just fine!
Good luck!