We decided to go down that route over ten years ago, and it was one of the best moves we made. It’s cooler in the summer (mind you, not by much this year as there’s still a lot of glass!) and warmer in the winter. It did make the dining room a bit darker, but it’s not been much of a downside. When we had it installed, we had people knocking on the door to ask about it, and suddenly they were appearing everywhere.
We decided not to go with the large national firms but found a reputable firm fairly local to us who were prepared to put us in touch with people who they had carried out installations for, one of whom invited us to see the finished article.