I feel that they did a nice job, and overall, I have no complaints. If I get time, I can try and get some pics of the install.
I do not want to get too specific on a public forum (site rules and all...), but I can tell you that we used the "Home Depot" guys (I'm sure you know who). My wife and I just moved into this house, and we elected to take advantage of the "1 yr" finance free program. We are currently working to pay off other "Up Front" home purchase expenses, so we liked the idea of postponing payment until we could better afford it. That weighed into our desicion a little.
We did not have another Trane contractor quote, though we DID have three other guys quote Carrier. One of the Carrier guys also quoted a York system as an alternative, and another Carrier guy also gave a quote on an Amana system. The Amana seemed like a pretty nice bang-for-the buck.
Out of the four contractors, the "Home Depot" guys were not the cheapest, but they were in the "ballpark" relative to what guys were quoting for similar Carrier equipment (Cheaper than one Carrier dealer, actually). This was particularly true after considering the current rebates being offered through Trane/Home Depot.
The "Home Depot" Trane installer was not the cheapest, but I feel they did a nice install, and thier pricing was competative with three other contractors in the area (though the others quoted Carrier w/ similar features, not Trane).
BTW, have you noticed that MANY contractors in this area look at you like you are from outer space when you ask if they plan to do manual J load calcs on a replacement system? ;)