We initially bought a bay window replacement, since I like fiberglass over vinyl.
Install and product went good.
Ordered later a few more, including slider.
Quality (hinges, handles) lower (admitted they don't make the 'good' ones anymore).
Service right after was good (quite a few things and several visits).
Replaced ALL other windows a while later.
All together ca. $25,000
Salesmen always follow up nicely, and if anything needs to done; mentioned the few smaller things, but offered to wait to combine service.
Called now that another handle broke (they are ALL junk plastic), and initial defect from installation (inside corner cut into seal, ripped) needs to be done.
Now (Install 2/2010) they demand $75 service charge for their lifetime warranty.
Conclusion: lots of effort on high pressure sales, lots of effort to 'upsell' (at least 10 calls to sell from vinyl siding to insulation to gutters). ZERO, NADA, NO service once they are 'done' with you.
Make sure to call them EVERY MONTH during their '2 year' after the sale, even if the window just needs a drop of oil.