Hi
We've used it twice as we're non drivers and no problems with it. Takes an hour and a half to 2 hours depending where you join the bus and traffic and you do get a full day there.
We joined it at the Universal Studios bus park as we were staying on site. It stiopped by Wet and Wild then Sewaold itself and of to Tampa then.
I think from memory we booked it a day or 2 in advance as i heard it can fill up so as long as you pre book it you should be fine.