I've dove/freedove both places but wouldn't go back- neither would my wife. Lots of biting bugs and some pretty overfished reefs. I did get to dive with whalesharks on Utila, check out my user's gallery, but tat was the highlight. I couldn't believethe lack of fish on Utila- like an hour long dive without seeing anything bigger than my finger.
The one thing they have going for them is that they are cheap, once you get there. Otherwise I could think of many other places i would rather go back to- many of which you can reach with your own boat!
Jon