I did a restore on my 4 and my battery is no worse, maybe even a little better than with 4.3.5. If I'd leave my phone on overnight sometimes I would lose 1%-2%. It charged up to 88% when I installed the GM, used it for about 30 minutes or so last night, let it sit overnight, and used it this morning to shoot out a few texts and emails and now it's at 87%.
With 4.3.5 I could get about 3 days of standby and 5 hours of usage before my battery drained completely.