I've driven many Hyundais (and the related Kias), and aside from the Accent/Rio, they're good cars. The Sonata/Optima are very good competition for the Accord/Camry, especially when price is added to the equation.
I've seen some of the upcoming Hyundai models and they're going to be very competitive with Lexus and the like. Remember when Toyota was arrogantly going to pit its new brand against Mercedes-Benz and everyone laughed? Now Lexus is treated as a peer. Don't laugh at Hyundai's plan.