I have played EVE for some time as a rather unimportant pilot battling in a big corp in a huge alliance that was fighting the back-then biggest alliance in the game.
EVE is nothing short of amazing in terms of what CCP is doing. They are one of the few companies actually evolving gaming and technologies involved. It is one of the very few "role playing games" where you instantly and automatically take on a role and play it both in and outside of the game - you decide to be a warrior, you play, act and talk like a warrior; if you want to produce or be a freighter pilot, you can also do that at just as much depth. There are no quirky flame-wars over what is "in character" or not, like in WoW on RP servers. In EVE, anything you do is automatically in character and perfectly suitable, at least to some degree. You can actually play a freighter pilot or a producer or miner/gatherer and nothing but that and be just as successful as a fighter, if not more! EVE really offers a lot and each route offers a lot of depth especially when compared to market-leaders like WoW. WoW's economy and crafting is quite frankly kindergarten compared to EVE's economy. Even the first, lowest items you craft in EVE have a purpose and will make you money while in WoW, you are actually just crafting to make it to the top-items and anything below is by and large useless. The battles you can find yourself in can be wild, imagine flying with a few hundred or thousand people from all over the world!
There are downsides to EVE, for me: it can be too much and get too real quickly. It has a LOT of depth and a LOT of that is happening outside of the game, so you will definitely have to invest more thought and reflection on what's going on, it can take time to learn just one thing. This outside-of-the-game is an integral part of EVE and one of the reasons it can offer so much. This can also make it very frustrating as a beginner while people in good corps and alliances have mentors or require you to spend a lot of time reading online. At the same time, anything you do is "real" and has actual consequences. Yes, you can loose days or weeks of progress if you do something very stupid. Yes, players have lost what can be estimated to be four digit real-world USD values. To really get full access to what EVE is really all about, you pretty much have to play in a corp and then special rules will apply of what you are and are not allowed to do. If you are a fighter, there will be a military-style drill of some sort. On this level, your actions can easily have even more consequences on a larger scale. To sum it up: EVE is no idle pastime and you do not just log into EVE and "zerg" through a few battleground inebriated without any consequences or danger. But if you like that, it is pretty much the best game around! Don't let the strange UI scare you off at first. Another downside might be that you will be very unimportant and expendable for quite some time; unlike in e.g. WoW where you get that satisfaction of really having killed some mob or a player, in EVE battles can be frustrating and drawn out, often without a clear 100% winner and seldomly do you get that same satisfaction of really having killed that one important enemy... you will be much more of an unimportant zerg; later on you can develop into a very highly trained and knowledgeable commando or a very well geared but strictly regulated and commanded fighting force. This might not be "fun" for everybody but it definitely offers you a lot of things that no other game can offer.
On the upside, a lot of that outside-of-EVE gaming gives TONS of fantastic opportunities for little software projects! A lot of EVE players with programming skills are developing something somewhere for themselves or their corp/alliance and CCP created a few APIs and services to openly interface with some of the game's information!