My 2011 Sonata has 61,800 miles on it. The oil and filter get changed at the dealer every 5,000 miles. I also run fuel system cleaner in it 2 - 3 times a year.
My particular engine is using 1qt of oil every 800-1000 miles. No obvious leaks anywhere under the hood or under the car. It is at the point where I check the the oil level every time I stop for gas. Power seems fine, and fuel economy has not changed. The car just uses oil. I just keep the oil topped off with conventional 5w20 and press on. Somewhat inconvenient, but not the end of the world. There have been reports online of early build 2011 2.4L Sonatas experiencing catastrophic engine failure due to total loss of engine oil. Based on my experience I can see why this may happen to people.
Would I buy another Hyundai...sure. Am I sold on DI technology...not really but it is becoming the status quo.