I can't speak for others, but I've been very happy with my Piper Glen.
I bought mine back in 1999, used it for 4 years at my old house, moved it to my new house and have been using it for 3 more years. I use it practically every day for 30 min and since moving in my new house at least every other week for 3 + HOURS during parties. In fact, because of my increased use, I'm paying roughly $60/month just for spa electricity. The "old" Piper Glens have two 5 HP motors and a circ pump. My only complaint about the design is that the circ pump should have higher output to keep the temperature up on cold nights, but if you use the spa for less than 1 HR, this is usually NOT an issue.
In terms of reliability, the only problems I've had were a bad ozone mixing valve (the valve with that funny name) and a connector on the main board that got wet, corroded and caused the board to go bad. Even though my tub was more than 1 month out of warranty, Artesian replaced the board free of charge. How it got wet is still a mystery, but it may have been due to a bad seal around the control pannel.
Most impressively, my Piper Glen has held up to the eleven (that's right, 11!) children in my extended family who seem to use it almost every weekend. It's held up to 5 year olds seeing how often they can press the buttons on the panel and how long the wireless remote can stay underwater and still work. It's held up to the 8 year olds turning the spa pumps on and off, off and on to the point that now I LOCK the panel when they get in. It's held up to the 10 year olds jumping off the fence and cannonballing into the spa. Oh, and did I mention all of the kids using the pillows and filter box top as floats?
Of course, then there are the adults. I won't even mention what WE do in that spa. And, YES, I've done that before too...
Through all of this, no break downs, no cracks, no tears in the cushions, no broken handles or doors, no jets that don't work. Just good solid performance that keeps me getting in that darn thing night after night. My tub literally changed the way I live, entertain and enjoy life. Without question, it's the BEST money I ever spent...
Peace and Hot Water Brother...
Drewski
8)