I like it. I have a friend in Fairbanks, AK who uses his smaller one every morning to drink his coffee, unless it's more than 20 below zero. He added insulation around the outside, but in the continental US I think that's not necessary.
No problems with it yet - I bought it used from a company that rents 'em out and replaces every year.
Very convenient. I've moved it up to 1st and 2nd floor decks alone, very stupidly carrying it up a ladder myself. Don't do this. Could've killed myself. But I did it.
I've two other friends that have them, both 150-gallon models. One uses chlorine, has let her chemistry get out of whack, and had to replace ("re-skin") the liner. She's also had to have the thermostat replaced. The other used bromine floater, and had to have seals replaced - possible connection, 'cause Softub says use only chlorine.
I started with the bromine floater they gave me with the tub, but switched when my friend told me of her woes. I'm trying out Baqua-Spa. Having just started, I can't evaluate this system yet.
I don't use the air jets. I like just the water flow, and don't enjoy the spray from the the bubbles.
I keep my (digital) thermostat at 102, and my thermometer say's the temperature maintained is fairly consistently 103.4.