We love ours! To keep water temperature constant, we fill a bucket and recycle the water through it for 5 or 10 minutes, then have our showers. I think there is an issue with all systems of this type. Once the gas cuts out so does the hot water. We have ours set to the lowest temp when showering and crank it to high to heat the bucket initally.
Bear in mind that we only use it and the ensuite when in company. Otherwise it's the kettle on the Ozpig to heat the water and cup it over.
However, we do think they are the Bees Knees for showering. The shower head is like one from home, and has an on - off switch on it, so that you can use it without relying on having a second person to keep things operating. We purchased ours from Anaconda at 20% off regular retail, and due to being a club member, got a further 20% off that! Made it the cheapest one out there for us.
Kit_e