If you like fantasy MMOs of any kind, I can't imagine you wouldn't like WoW.
I have played at least a dozen MMOs over my 15+ years of playing them; WoW is the only one I still play. (Rift open beta tomorrow... get to give another one a shot now!) Most MMOs, I haven't even paid for beyond the initial trial month or whatever was given free, except for 1 or 2.
Having just started a Worgen Druid, I can honestly say, their beginning area and the storyline that takes you through it is the best of any of MMO I have ever played. I know people starting out probably don't want to have to buy the game and all the expansions just to play a Worgen, though, but even the other starting areas are different after Cataclysm and were never hard. (Makes me want to go try a goblin now too!) If you're level 1 trying to kill level 6 creatures, you're probably going to die. (Also, if you died and took the resurrection from the spirit healer "ghost" in the graveyard, you get a 10 minute penalty to stats... go back to your corpse and take the resurrection there!)
I enjoy leveling / questing in WoW... if you think that is a grind, you probably have never played EQ. I know that's a completely different animal, but in that game, there was nothing TO do except get into a group and sit in one spot in a zone (if it wasn't already camped) and pull creatures non-stop for hours to get a FRACTION of one level; no questing, no soloing, RARE gear upgrades... The questing in WoW keeps you moving and earns you gear that will keep your equipment sufficient for the next zones... you definitely don't have to go BUY gear, but as you earn money, strategic upgrades will certainly help. (Of course, my worgen with 4 peices of BoA gear + guild xp bonus has me absolutely shredding everything right now!)
Starting out, you need to decide what role you want to play and play your character accordingly. If you are trying to beat stuff up with your staff as a mage... you're doing it wrong. If you're trying to kill stuff with your bow as a warrior... you're doing it wrong. The first 9 levels are spent pretty much just teaching you how to pick up a quest, how to hit a skill button and how to move around the game. Once you hit level 10, you open up your talent trees and your character will really start to grow in whichever direction you want. Of the 3 major roles (damage, healing, tanking) a couple of the classes can do any of the three (not simultaneously, of course) and most other classes can do at least 2 of them. Even the pure damage classes (mage, hunter, rogue, etc..) have significant differences that allow you to change your playstyle.
You can solo to max level in WoW, although grouping will speed it up a bit and help you get better gear through dungeons. Enter the dungeon finder... once you hit level 15, you can put yourself in a queue to join other people and it will automatically teleport you to a level-appropriate dungeon which will provide you with bosses to kill and an extra reward for finishing the dungeon. Yes, sometimes you get idiots, but for the most part, people know them and will fly through them.
If you have a friend that wants to play as well, or already plays and wants to start a new character, you can link your accounts together through the "recruit-a-friend" function and earn some nice rewards including +300%xp (I think it is) when you level together. As well, there are plenty of guilds on any server that will take anyone in. Here's another way to find people to hunt with and now, with Cataclysm, you can also receive some additional benefits (more XP for quests & kills, more gold, faster movement speed, etc, etc...) as well as get you into some more dungeons and raids or even PvP (you can still do all those things without a guild, however).
I know this is long, but I enjoy WoW and just wanted to add my thoughts... last thing I wanted to comment on was the graphics. A lot of people rag on the game for the "cartoonish" graphics. The game was never designed to have hyper-realistic looking graphics. In my experience, most games that try to do that still look like computer graphics and never achieve whatever it is they were trying to and usually sacrifice a lot in terms of gameplay. The artwork and design behind the zones of WoW have always been appealing to me. The ambient sounds and background music really enhance the feeling of being in the game. They've put together a huge variety of environments and they do a good job of making you feel immersed in the game. Aside from that, the number of "easter eggs" and references to outside culture is huge. There are plenty of humerous events and things to keep it refreshing. "Camel Tow" quest in Uldum, anyone?
Bottom line, WoW is very polished, pretty well balanced (still tweaking after these last patches), provides massive amounts of gameplay, offers regular content additions (including new raids & PvP for free after an expansion), is well maintained and is the most successful MMORPG ever (by a huge margin). Is it for everyone? Obviously not... but with 12 million subscriptions, they must be doing something right.