We had 12 windows (3 brick to brick, one of which was a bay window) replaced in the summer of 2011. Decided to wait a while till posting so we could report any defects that arose after the work. Well, there really are no issues that we're aware of.
Our salesman, (who I think may not be at the Alta location) was professional and quite knowledgeable. His price was 10 - 15% less than any of the others, but his interest in our needs, and the many favourable reviews, is what caused us to choose them. The installation was done by a 2 man crew over the course of the day, and they didn't go home until the job was done, even though it had become dark. This was impressive. They knew what they were doing and cleaned up any mess.
The next day we did notice a small tear in one of the screens, and a couple scratches to the aluminium trim. The screen was promptly replaced and the scratches nicely touched up.
One thing though, some maintenance is required as the metal lintels above the windows were not capped, and require periodic painting. I know many suggest not capping the lintels as this will apparently prevent water from draining properly. None of this was discussed at either the time of the sale or installation.
Anyhow, overall we're very pleased with the job.