it will be a bit sharper than the air on 1280x800 because it's the native res for the MBP. but hell, i'll live with core 2 duo rather than the low resolution of MBP, because screen is one thing that i look everyday, not processor speed.
it all depends on your use though, if you are a light user, u might as well staying with the air.
the MBP with Hard disk will feel much much slower than the air, except you buy an SSD and put it on the MBP. it will scream!