usually F2P quickly degrades into what can they shut off from the game to make people want to pay...
-Extremely long "Leveling" times to be even able to use certain items to help sell XP boosters (XP and Money are basically two sides of the same coin)
-Time limited items that disintegrate within days or hours
-Items that can only be realistically obtained via cash for any decent amount of time
-instead of a payment ceiling (say 50.00 retail on a boxed game) you can easily spend 100+ or more for items and not have the stuff a week from tomorrow or even half the "game"