Nothing at all.
I traded in a 1999 Sonata for this car in Nov of 2003 and it is my third Hyundai. The car has been remarkable in terms of ride, acceleration, quietness, and reliability. Everything from the interior pieces to the bodywork is very tight and the improved quality of this manufacturer shines through and through. For the price, I feel I received a great deal and until Hyundai stops selling cars here in the US (not likely), I will continue to look at them first for future car purchases.
If you had a good experience with your Hyundai, consider yourself one of the lucky ones. Read the other reviews!
I also am very, very pleased with my 2004 Sonata. As a long-time Honda accord owner, the Sonata, to me, is the superior car: Better ride, comfort, power, gas-mileage and $8,000 less than the Accord... AND it has a MUCH better warranty... What's not to love??
What's not to love about the Hyundai Warranty?... well... real simple... if you should purchase a manual transmission (as I did)... and you should encounter a 'damaged flywheel causing failing clutch (the clutch will NOT engage in shifting to any gear)... the warranty that is so advertised -- CLAIMS absolutely NO RESPONSIBILITY. In other words, it doesn't matter that this problem should occur in very low mileage 15,000+ -- you are on your own (you will incur the total expense to repair should you decide to)!
The damaged Flywheel IS HYUNDAI'S RESPONSIBILTY. A defective Clutch Pressure Plate or Centre Plate will damage a Flywheel. Consequently, a defective Flywheel will damage the Clutch.
In the UK it is well known that Hyundai have a problem with the Accent Range fitted with manual gearboxes. Hyundai clutches and manual gearboxes are a known weak-point. Speak to the mechanics and they will tell you the truth. Not the salespeople who are only concerned about sales commissions. Please persist and make a nuisance of yourself. It pays off in the end.
I have an update to the original review. No problems at all in 31,000 miles. The car is still very solid and smooth. As stated in my Santa Fe review, Hyundai gets a first look on my next vehicle purchase and no, I do not work for Hyundai.