Nothing yet, but it's still new.
This car handles well and the ride is very smooth.
The power hesitates for a brief moment when the accelerator is punched; possibly due to the automatic transmission.
The trunk lid profile tends to somewhat block your rear-view when backing up.
Lots of great standard features that are options in other manufacturers, such as air conditioning, electric door locks and windows, tilt wheel, CD player, cruise control, 8-way adjustable drivers seat, and dual front and side air bags.
I was originally shopping for a Spectra, but I found that I could negotiate a lower price for the larger, more plush Optima. (I paid $12,895 and they even threw in a couple of tanks of gas, free car washes and an oil change!)
My mechanic told me that parts are quite expensive for the KIA line, as there aren't many aftermarket parts available yet; although I haven't personally looked into this aspect.
Manufacturing seems to be done well, with no seam gaps, etc.
Well engineered with a very solid feel.
I don't understand how your review of this car is posted when you have driven this car a total of 500 miles. Wait another 10,000 - 20,000 miles and you will regret ever buying a KIA. Their customer service is awful and their cars are ridiculously unreliable. I was given a KIA Optima by a family friend and I still ended up losing more money on repairs than if I would have spend thousands of dollars on a quality car from a company like Honda, Nissan, or Toyota. Please don't mislead potential customers of this awful company by writing reviews before you have even driven the car a thousand miles!