Hi have had the Lay Z Spa about a month and so far so good despite some fairly rough treatment from the kids and me. I just read all the stuff about them breaking down with horror having missed them before I bought. Probably would have put me off so really glad I didn't see them.
I read about heating costs being about £4-5 a day and this is probably about right judging by the amount of time the heater stayed on initially. To reduce this cost make it greener and make it quicker to heat and slower to cool I have insulated mine. It sits on 100mm of celotex wall insulation and has another layer of 75mm wide high tec multifoil insulation inserted between outer fabric and plastic sides, so you can't tell. Left over multifoul insulation is cut to shape and placed over the top when not in use. I reckon the heating bills will be cut dramatically and its warmer too.
This lot wasn't cheap mind, about £140 but will hopefully pay for itself. Thought this idea might be of some interest in these days of far from cheap energy and global warming.