There is a LOT of expectation and speculation being placed on the 2011 Sonata, from consumers as well as industry competitors. Hyundai has been making all the right moves over the past 10 years, and they're about to pay off (i.e. dumping all profits into R&D, encouraging internal competition from Kia, maintaining the 10-year warranty).
The fact is that Toyota - irrespective of quality woes - cannot and has not made an interesting car for the North American market in years now. Honda, on the other hand, has stuck a little too close to its no-longer winning formula and has failed to show any willingness to experiment or take risks with its product lineup.
Take all of these industry conditions into account, throw in a well-made, well-priced, and well-endowed Korean car into the mix, and you have all the right ingredients for the underdog to become top dog. Of course, Hyundai still has a long way to go before that happens, but the new Sonata is a helluva start...