It certainly is walkable because last year I walked to Universal from the Best Western Movieland hotel which is directly opposite Wet n' Wild. There are sidewalks all the way on one side of the road and it brings you to the bus/taxi pick up area near the car parks. In terms of actual walking distance it would have taken me about fifteen minutes to do, but it was nearer 25 because it took so long to cross certain roads.
However, it's not that easy. At one of the junctions, I found the lights just didn't work - I pressed the button again and again and waited for a good five minutes but never got a WALK symbol, so you had to guess when it was safe to cross (across six lanes!). Then at another junction there were no pedestrian lights at all! Okay this road is only two lanes wide, but Universal has quite helpfully decided to plant large bamboo style plants right on that corner, creating a blind spot so you can't see if there's any traffic coming your way (and drivers can't see you until the last second either)!
So if you're not confident about crossing roads 'blind' then you may still want to consider a taxi!
