We were at WDW last month with our dgd 6 months. She did fine on all the rides. She even rode Dumbo.
We didn't take her on the Kil. Safari ride. I thought it would be too bumpy.
If you have a sling, take that along. Sometimes it's just easier to hold the baby in the sling while you're going from ride to ride (especially in Fantasyland), then to put baby in stroller, walk to next ride, take baby out of stroller, etc. KWIM?
BTW, I know you didn't ask about the buses and monorail, but in case you didn't know, you don't have to take baby out of the stroller and fold up the stroller for the monorail (you do for the buses). We stayed at the Contemporary this last trip and what a breeze it was just putting baby in her stroller before we left our hotel room and we didn't have to take her out once (until we got to a ride). Taking a Disney bus with a stroller is such a pain. If you have a car, drive to the parks instead of using the buses!
HTH
Mary