Buddy willing to stake me 500... take it?

[luckycharms]

Ok, I am a well read, fairly experienced poker player, but I have NO bankroll. I spend all my winnings on dates/college/food/party stuff. Anyways, my friend has offered to give me $500 to play with at Turning Stone Casino or online. The terms are that if i lose it all, I have to eventually pay him back $250, but however much I win, i give him 25%.... I have the potential to win a lot, and I think it's a good deal for me. Thoughts?

Assuming that I am a proven winning player, and have recently gotten more consistent with my play and winnings, is it a good deal for him?