Have had it done on current car and previous. TBH, I don't think I'd do it again. Very expensive and I'm more than a little dubious if its any more beneficial than DIY detailing. i'm not a fan either of the theory that you never need to apply anything else to the car again for 1-2-3 years. I kinda like the ritual of regularly applying a wax / applying a sealant or whatever, so...
Next time I think I'll stock up with some products and do it myself. If you've the time/energy to DIY, its far cheaper and more rewarding I reckon.