Keep in mind that most reviews are written by people with bad experienced but I read this off of amazon (some others like it too)..
"Software/Processor:
This is where the unit really fails. It is extremely slow and the software is buggy. Several times (4-5) in the 3 days I have used it the unit has completely frozen, would not respond to any input what-so-ever. The only fix for this was to shut my car off for several seconds and start it back up. The software is also very, very slow. It takes 45 seconds to even become responsive after my car is turned on. When switching between screens there is a lag of between 5 to 30 seconds. It gets frustrating when you press a button several times after no response only to have 3-4 clicks register at the same time 4-5 seconds later, this happens quite a bit when changing volume. This appears to be a combination of the software and a slower processor than is needed. I am unsure if a more efficient software update could solve this issue as it is so bad now. "
Amazon.com: Kaleb K Reynolds' review of Pioneer SPH-DA01 AppRadio 6.1-Inch In-Dash...