Our new home was built with Decora windows in 2003/2004. The casement style windows were tolerable, but all of the sliders were extremely poor in build quality. All leaked significant amounts of air where the two panes met in the middle of the window. The one in our living room was so bad that on a windy day the breeze could blow out a match placed near it. During winter there was always a ridiculous amount off ice on the interior of the windows, despite keeping the humidity levels in the house very low. We also had several double panes lose their seal over the span of five years.
As for the service, it was a joke. For the living room window that leaked so badly, their solution was to stick a piece of cardboard under the track that the windows sits in to raise it higher. Not only did this not work, it left us with a black mould-ridden piece of goo in the window that I only discovered because I did some spring maintenance/cleaning.
In the end, the builder stopped using Decora and moved another manufacturer because of all the issues the Decora windows had. In our case, the builder replaced the worst of our windows with a different brand that were of significantly better quality.
If you builder is using Decora windows, either pay to have them use a reputable brand, or find a different builder. Otherwise, you'll be looking at buying new windows in less than 10 years.