All I know is that if my PS3 didn't have BC it would be a huge issue for me.
My PS2 is getting old and I have actually have one PS2 title that my stepdaughter likes to play when she comes that works on the PS3 but won't work on the PS2 anymore ( the disc is scratched a little but it seems the PS3 handle that better than the PS2).
PS : forget the Wallmart 100$, the bundle sold out in every retailer and most of them didn't match the Wallmart thingy...
Edit : my PS3 BC gets used a lot. So far I have played GoW3 and FF XII on it and my step daughter who comes visit us 3-4 times a year is a big fan of Dynasty Warrior, Soul Calibur 3 and Tenchu and she spends 2h+ per day when at my place playing those old titles on the PS3....( I didn't buy the latest Dynasty Warrior on PS3 as the new combat system seemed lame).
PS3-Xbox360 gap : 1.5 millions and going up in PS3 favor !
PS3-Wii gap : 20 millions and going down !