This is not wholly a complaint so bear with me - with reservations I do recommend the product.
I bought a 20' x 9' Four Seasons sunroom extension with the beautiful curved glass, triple-glazing and laminated pine beams in 1990 - at that time they gave a five year guarantee (which sounds pretty pathetic for an installation costing (then) well over $20K). After seven years very satisfactory use I found there was condensation happening inside some of the glass panes (i.e. the seals had gone) and I alerted Four Seasons who came and inspected it and agreed that, really, all the glass should be changed. They insisted that this would have to be an 'out-of-warranty' repair and quoted me $8K to replace all the glass with new - and for this they would give me a TWENTY year 'sliding' warranty (meant the replacement cost would be shared as the years advanced towards twenty!).
All the glass was therefore changed for the agreed amount and now, eighteen years later, the sunroom has done well and there have been no more failed seals to date.
Apart from having to pay a swingeing extra $8K for their manufacturing mistake (they obviously fixed the problem) I can say that I have been very satisfied with the product and would buy it again IF, and only if, I could negotiate a twenty year warranty on any failed window seals.
A final point. The windows in my sunroom should carry a sign "Burglars - if you must break in, please use these windows" because they are held closed by the flimsiest hardware. Maybe the new models have fixed this but I had to reinforce mine.
Advice: Lovely sunrooms but (1) Make sure you negotiate a fair warranty and (2) Check that the operable windows have sturdy hardware against break-in.
Product or Service Mentioned: Four Seasons Sunrooms Installation.
Reason of review: Damaged or defective.
Location: Toronto, Ontario