Runescape had some good housing, but there were some definite flaws to it. The customization was nice, but (like seemingly everything else in that game) it was tied to a skill, and so if you wanted your huge lavish mansion you had to grind up making various bits of furniture for exp that you would then throw away because you have no use for them beyond that. It was also hellishly tedious; you had to obtain wood, go to a sawmill, get them turned into planks, take them to your house, and do something with them, and your inventory in Runescape is rather small, so you're doing this quite a lot.
a way to stop this though is some servants you could get, but they required to be paid... more expensive ones could carry more at a time and came with neat abilities. But, they were expensive, like everything else to do with houses- you had to buy (or make) nails, chop down (or buy) lumber to make into planks (which you pay an NPC to do). Worse yet, to get any reasonable experience to level up the skill to get new furniture, rooms, and generally a not-meh-home, you have to sink in a lot of in-game money and/or time. It was neat, but it took a long time or deep pockets to get a nice place to live.
WoW's houses bug me; a lot of them are sitting around with nobody in them... but they're also destroyed. Barely any building that has no inhabitants is in okay condition. While player housing is nonexistent, if you did want to RP, it'd be nice to use an empty building rather than cramming everyone into the vague, nonexistent "room at the inn" everyone seems to stay at.
short version!
Player housing is a cool, neat idea. I have yet to see anyone do it really well. Runescape's is okay, but has major flaws.