Korean Vehicles are cheaply made, which is reflected in both the price and the quality.
most independent consumer reports rank kia as the poorest quality vehicle, whereas Lexus is the top rated vehicle for quality. Toyota follows after.
Yes, you get a good deal on a vehicle, but if you keep it past the warranty, you'll spend all that saved money on repair work and headaches.
If you trade it every 3-4 years, then I say go for it. If you get a junker from them(as most of them are) you'll still have the warranty, or Lemon Law to fall back on.