MMORPG's take over your life, literally. Think twice before getting sucked in.
Anything can take over your life if you don't exercise self-control. I've played WoW since beta, have maxed out a few characters and on average don't play more than 8 hours a week. I do play other games, work full time and am in an evening MBA program. Besides, MMORPGs have a social element which is quite engaging and enjoyable.
Pricewise, online games are extremely reasonable. $15 a month is really not much - that's ~40 hours of entertainment for the price of going out to a movie for me and my wife.
Graphics wise, WoW isn't anything spectacular or next-gen. It does have native WS support, and has some fun lighting and spell effects. It has a cartoonish feel which is reminiscent of previous Warcraft games. The game itself is great - with a multitude of quests, two huge landmasses with dozens of zones. It is easy to group or solo your way from level 1-60, and at 60 raiding (even if you only spend 2-3 hours, 2-3 nights a week) is the way to go to get better gear. With an expansion due out sometime this year?? it is a great introduction to the world of subscription based gaming.