I have also tried both. Everyone is different. For me, Seroquel XR made me feel loopy during the day, for a longer period of time, compared to IR. It affected me at work, where I felt drugged and actually made a false excuse to others that I had a bad cold so that they wouldn't get the wrong idea....until my pdoc took me off of it. Also, it was harder getting to sleep on XR. I also didn't find it as effective at preventing symptoms compared to the other one.

I am currently on regular immediate release Seroquel. It helps me get to sleep much faster, which is important to me, since I struggle with really bad insomnia without the help of strong meds. I am on 600 mg now, and while I still feel the hangover effect early in the morning at least half the time, it goes away after a couple of hours. This is an improvement when I compare the hangover effect to XR. Rule of thumb though: If you need to get up early, make sure you take it early enough at night, or you may experience times you feel very dizzy, which is especially dangerous if you need to drive. If I take it early enough, I will experience little to no hangover effect.