In some respects new builds are done better as the codes have gotten stiffer on some things. Most contractors have found other ways to short change the product though like using OSB instead of plywood for the roof sheathing. First, create a whole list of the issues needing to be resolved. It is much easier to get them to come punch it out in one shot. Second, learn about how to properly resolve the issues so you can ensure they are doing it correctly. One thing I have seen numerous times are the doors will not be shimmed or nailed properly. The doors will last for the year warranty typically, but after that they do not open and shut correctly. General contractors don't like showing up, but hopefully they want to maintain their reputation for a little longer. They are notorious for shutting down and reopening in another name. I am in remod and haven't changed my business name the entire time. (something to look at in the future when trying to find someone) Feel free to send me a private message though with specific questions and I will try to answer them best I can. Bottom line, knowledge is your friend.