We purchased a 2004 Newmar Northern Star 5 years ago. We have been impressed by the workmanship and the customer support that Newmar has provided us. I would not hesitate to purchase another Newmar.
For any used coach, you need to get complete maintenance records and you need to make sure they knew what maintenance should be done.
Look to see if the coach has the paint checking issue - if you ant more information, do a search on this forum. This issue was not just with Newmar but with other manufacturers on coaches from about 2000 to 2008. I have seen it on many other brands - it is a defect with the sidewalls and many coach manufacturers used the defective sidewalls. The problem gets worse over time even if the coach is stored under cover.