Rather than looking at all the opinions, why not look for yourself. You are the best judge as to whether or not you think the screen looks great. I would suggest going to your local Apple Store and check out the 20 and 24 inch iMacs. Maybe bring some photos on a flash drive to compare. Even if there was nothing but rave reviews I would still look for myself before buying.
If you are concerned about their return policy then buy from a (insert major electronics reseller) with a no questions asked 30 day return policy.