My demanding Border Collie would do fine with an apartment. =D He just naps and maybe plays tug with Fozzie when he's inside, anyhoo. As long as there was an area for him to play off-leash everyday, and he got as many walks as he does now, it wouldn't be much different at all.

However, that is pretty generalized, and most people are NOT dedicated enough to own a high-energy dog with or without a yard.