I also have both..... i didn't play F1 that much... but revisited it recently and tried the suzuka track to get a comparison to gt5p.... i was surprised at how much i did like it..... sun effects are good... it's feels very fast obviously driving an f1 car around.....
then i put gt5p on straight after and it really really made me realise just how bloody good it is

much much smoother, clearer.... and although you are driving slower just more engaging... and more fun.. the clarity in 1080p is just amazing.... it's easy to get used to it and forget just how good it is..
I honestly can't wait for the full blown gt5....