I have an 04 Sedona, it's always having problems. I read somewhere that the 06/07's are suposed to be better though.
Mine has 25,000 miles on it...I can't tell you how many times it's been to the dealership. Mostly for minor things...the cd player quit working, the plastic molding on the seat broke, the plastic holder for the gas cap broke, the hatch light quit working. I'm currently having my first real mechanical/safety problem that Kia is still trying to figure out after about 4 visits...sometimes it loses power and either almost dies or actually does die.
The gas mileage is terrible....the best I get is 18. It's usually closer to 13 for around town, short trips w/the AC on.
I should also say that I got it 1 year old with 8,000 miles. It had been a dealer demo so I'm sure it had been driven hard. BUT, I didn't expect to have so many probems so soon.
Car seats have installed easily. I've had a roundabout, decathalon, boulevard and snug ride in most of the seating positions. One nice thing is that the bottom latch anchors have a little indentation in the seat fabric so they are super easy to get to. Mine has lower & upper teathers in the middle seat and upper in all 3 positions for the 3rd row (i think)