I've bought a used car at Great Lakes Hyundai and had a lot of work done there on the van (I no longer own) and my 2006 Hyundai Sonata. I've been doing business with them since about 2008.
The dealership is clean and the employees are friendly. They wash your car after servicing it. They are very fast and professional. The waiting area is comfortable and they have great coffee. They can loan you a car if it's a serious issue (e.g., there was a drivers' seat recall where they had to ship the seat to California). As people, I really like them. Everything is wonderful. What's the problem? The repairs cost an awful lot. It's frustrating to have repairs that have to be done at the dealership because you know you're going to pay.
I had my car towed to them because it was not running right. I said "this is throttle position sensor problem." Their answer; "it's $99 to diagnose the problem." Of course it was a throttle position sensor (error code made that clear) and the part was $41. But the LABOR was about $250 and there was a $15 charge for "shop supplies." With tax, my bill was about $350. The national average from repairpal.com is $168-256 (the part averages $82-146). Ouch.
I have nothing bad to say about Great Lakes Hyundai as people or as a business; this is just the nature of dealerships I guess. I have to vote with my feet and avoid there service department unless it's something that only the dealer can fix.