Yes, I do consider it to be a good game. First of all the gameplay is rock solid, the UI, mechanics and controls are all responsive, satisfying and accessible. This is really a strong point of Blizzard's design, if you just open any of the games they've released since 1999 and look at the main menus you will notice that they really are noteworthy for being animated, atmospheric and functional. In warcraft 3 the way the wooden tiles fall from the top, the whooshing in starcraft, the fire and darkness in Diablo.
This might seem superfluous, but if you think about it WoW is ALL interface menus; inventory, skills, talents, loot, pets, equipment, hotbars etc. A fair amount of the game is dealing with these windows and they just feel satisfying to use. The whole system of navigating the game feels like an oiled brass engine that's been running just long enough for all the pieces to wear in.
The art design, animations and graphics all feel in tune with the setting and subject matter. It's widely varied and is updated to keep pace with newer hardware.
The mechanics are engaging compared to other MMOPRGs but NOT to FPSRPGs; people either like the RPG mechanics or they don't, but if they are going to like an MMORPG I would bet that this is one they would like. The progression is snappy and accessible but gradually becomes deeper. It is not the most hardcore but it satisfies most when it comes to end game content.
The story is really the most variable aspect in terms of quality, but the lore that's spread out over every continent is quite engaging, a universe all it's own. As a sequel to the Warcraft strategy games it brings nearly every plot point and character to a satisfying end or continuation and expands upon probably every aspect of the original games and what sequel has ever done that to such a successful extent?
With the expansions they've added a new plot every couple years, some more successful than others but the content and gameplay mechanics they've added ensures that there is content available for nearly any playstyle or taste.
It's a roleplaying game, centered on character building and multiplayer, this won't appeal to some, but it's less tedious than EVE and not as twitch as Planetside 2, in many ways, it's a goldilocks game with really great interface, impressive art design and is perhaps the best sequel ever to one of the oldest, and well selling PC strategy games.