I used Zofran (brand, not generic, as I am not sure it was available as a generic back then) with my 2nd pregnancy. It didn't "cure" the nausea, but it got me to the point that I was FUNCTIONAL. To me, it was a Godsend. I only wish I had known enough to ask for it with my first pregnancy. I guess my nausea wasn't quite bad enough the first go-round for my doctor to suggest it. It was very expensive and I was functional for my first (miserable, but functional, barely)... but the 2nd time was worse, and I had a 2 1/2 yr old little boy running around that I had to be functional to keep the house from getting burnt down.
I would use it again in a heartbeat, if I were pregnant and sick like I was with my first 2.
ETA: As for safety? Well, my daughter is now 11 and she is a straight A student and does lots of extracurriculars. She is in no known way at any disadvantage physically or mentally. In fact, she is smarter than the average bear... ;)