well- if you want sirus/xm/HD radio- most of those all in one units w/the touch screens that i've come across- require an additional add on- also- if you want the steering wheel controls to work- same thing....
rearview camera....
i know a lot mention that they have bluetooth-but i havent found clear indications if the bluetooth microphone is built in or can use the kia built in microphone.....
and of course - you gotta find a fascia that matches the head unit size- i've seen 3 different sized openings available on different facias so far....
all done and said- yup- putting together a really sweet system is gonna be a fun job
i've even come across a an addon that plugs into the diagnostic port and runs to the headunit- lets you set up your own engine display gauges- and also has an event recorder to replay your track runs and what nots....
oh yeah- jumping back to the GPS ones- you gotta look at the anntena that is supplied--- some are really goofy/big looking- same thing if you are looking to rec'v over the air broadcast tv-- one i came across had a cube like 2 inches square- with a 6 in whip antenna attached...
another neat feature i found on one- it came w/the backup sonar sensors in addition to the rearview camera....
lol- now that i think about it---
i think we need to create a spread sheet with weblinks/brand/model/features so that comparisons could be made.....
well - like bbsoup32 said- pioneer does have a few things going for it- a huge DYI community- and the programable OS--- after all- wouldnt it be nice to change out the colors and schemes and remove icons for features you dont have or use?
i am looking forward to the first north american manual a/c koup w/a full indash set up w/touch screen and programable OS that has reverse camera,sirius or xm,HD radio, broadcast tv, steering wheel controls retained, and koups bluetooth microphone useable

(i prob left out a few features - lol)