I have and I'll be there again in July. Bergen really isn't a city where you need an organized tour. The hop-on-hop-off bus works fine, provides a good overview of the city, and makes it easy to get on and get off. Unlike other cities, it wasn't overly crowded, either, which made it a more reasonable option.
The views at the top of the mountain via the funicular are worth the ride. Also, the fish market is worth a stop and the fish soup is to die for.
