I am a big fan of pioneer head units. I bought 5050 around 2 years back and its just amazing.
Their best features are:
Looks : sexy look, neat and clean. it has less button on front which make it good looking. It has a joystick for all functions in its volume switch. the look n feel of these button is plush
Panel Down: It’s a panel down model. which saves CD unit from dust and increases it beauty
3.Sound quality: Great sound output it has, present equalizer is great combination and good bass boost
Back USB and AUX: since has the USB and AUX connectivity from back side, you can keep your USB or AUX device in dashboard..
Two Line Display: it has 2 line display which gives you the complete information about on going track
The only gap I found is you can not access preset fm station randomly, you have to access the sequential manner