We've had our Bullfrog up and running for 3 months now and have enjoyed every minute. No problems whatsoever with the tub under almost daily use. At about the 1 month mark the water turned green and unpleasant, so I drained/refilled. Not sure what happened since I followed the proper treatment regimen (I thought), and it's been fine ever since.
So far it's everything it was advertised to be and we're happy with our choice.