I just recently switched to vyvanse from Adderall for the once a day dosing schedule (ZI was taking it twice a day and I kept forgetting the second dose). I've had a good experience with it. For me, it's "smoother" than Adderall, I don't really feel it kick in, it's more like I suddenly realize I'm concentrating, productive, less hyper and I've gotten tons of stuff done. I had some nausea and headaches initially, but they went away. No other side effects. I've been on stimulants since I was 8 (I'm 30) and for me vyvanse has had the least amount of side effects than any other one. And I've been on most of them...