pioneer headunits?

[KBCnick]

how is this one?

Pioneer DEH-P510UB (dehp510ub) - Car Stereo Head Unit In-Dash Receiver - Sonic Electronix (http://www.sonicelectronix.com/item_17693_Pioneer+Premier+DEH-P510UB.html)

[05_ZX636]

i have the 5100 which is great also. I really like it, but im tryin to find a kenwood x-991 now