City of Heroes is a great MMO to start with for first timers or people intimidated by other established MMO's.
With all that said I think for those just getting into MMO's (Massively Multiplayer Online) or may find the other's available this is a great game to pick up. I might also add that for those who have had their fair share of the fantasy themed MMO's with their swords and orcs City of Heroes is a great alternative.
COH keeps the archetypes simple, at least it looks that way on the surface, which is great if you're just starting out. You'll find each archetype has an obvious strength/weakness and a role their designed to perform in group situations. One of the great things about COH versus other MMO's is that you'll find that you don't have to have the "perfect" group combination to experience most of the game. It is possible to do missions without the coveted "tank" or "healer" role, it may not always be as easy but it by no means impossible as the mechanics in other MMO's have taught you.
Character creation,as you've probably discovered by now, is one place the game really shines. The limits are almost that of your creativity, it is not uncommon to play the game for months or even years and still not see a character similar to your own. From capes to chains you really can create just about any look you'd like, although some costume pieces must be unlocked later in the game. I recommend you take a look at some of the screenshots of the various character models in the game if you have not done so already.
The graphics of COH in my opinion really are stunning, the character models reflect the classic superhero body structures and the city itself is simply amazing. Power effects are great initially, but in time you may start to be annoyed by some of the toggle (on until you turn them off) abilities, especially if you're one of the melee classes. Each zone of the city has it's own feel and style, anything from the dark gloom of ghost towns to the hustle and bustle of a modern day metropolis. One of my favorite pass times in the game is simply logging in and just flying around the city.
When it comes to how long this game will hold you, for most gamers it won't be as long what you may be used to in other MMO's. To me COH seems to lack a staying value, after so long it begins to lose it's appeal and it starts to have a "been there done that" feel to it. So while still a great game I find I can spend about a month or two at a time with it before I feel the need to move on.
COH is a great game when it's all said and done, but don't expect to play this game for years to come. I find that the game is great in small doses or as a break from other games. If you're just starting out with MMO's or not interested in some of the alternatives you can't go wrong by picking up a copy.