The main issue is that you need longer wheel studs and it puts a lot more strain on the studs an hubs risking damage. There are hub rings that have wheels studs built in but in general they are weaker than the stock set up.
My wheels have a 1.75" spacer in the rear, I havn't noticed any major ride quality issues, although I have heard about the strain. Also I was able to put wider tires on the back as a result of this. I should add that I have a wide body, so it might look a little different. Best picture I have available showing the stance is one from a few months ago... Hope this helps!