With just about 9000 miles, my Sonata is running with no problems. The fuel economy has been as expected (I usually average 28 mpg per tank). Although some say its a "Lexus-like" ride, I'd say that's a bit of a stretch. The interior (especially the center console) looks great and the amount of standard features really won me over. The 4-cylinder engine does run a bit rough on cold days but usually is docile unless its really pushed. The transmission does tend to upshift quickly on the automatic (I believe in order to give better fuel economy). So far I don't hear any rattles in my car. I hope to keep the Sonata for a long time, especially because of the great warranty.
USB/iPOD/Aux input inside the center arm rest. Easy to use controls with solid feel to them. Quiet ride. Beautiful dashboard/center console. Handsome, timeless exterior styling. Cavernous interior and trunk space. Great powertrain warranty. Hydraulic trunk and hood mechanisms. Reliability so far.
Smoother 4-cylinder engine operation. Gear ratio adjustment avoid early upshifts. Sharper handling.