I can has Star Trek (Online)
Unlike LOTRO, I haven't opted for the lifetime membership yet. There were enough issues at launch to cause me doubts, and while I never regretted the lifetime sub for LOTRO, it is a big chunk of change to plop down on a game you're not sure you'll stick with.
In some ways it doesn't feel like an MMO. I think it's a combination of the omni-server/instance system and the fact that we spend a lot of time in our ships. In most MMOs you have distinct servers and you tend to start recognizing names. In STO, there are no servers, just instances of the same space used to keep it from getting crowded, so you don't end up running around with the same people day after day.
The story line of the "main" campaign, the episodes, are great, with plenty of callbacks to various Trek series. And there are plenty of character and ship customizations to keep pixel-crack junkies happy for a while.
Having two systems to learn, ground and space, isn't a daunting as it may appear up front, as both are pretty easy to learn. Fortunately the designers didn't succumb to the twitch mentality used in FPS games and the Star Wars Galaxies NGE for the ground. Space is somewhat simplified with limited 3D, so you don't have ventral and dorsal arcs and you can't roll your ship. I consider it an acceptable compromise, especially considering the source material.
There are some weak points to the game, besides a lack of community. The crafting system blows and some of the other systems are clunky. These may be improved, back again to not having the lifetime membership yet.
In the funniest bug I've ever seen in an MMO, there is (or was) an issue in visiting bridges. Your ship has a bridge where you can walk around, with your bridge officers hard at work at their stations. You can also invite your friends to hang out on your bridge, because it's cooler than hanging out in your mom's basement. Well, when I went on my Klingon faction character's bridge, all the crew were Starfleet. I chuckled and told a friend who was online about it. On an impulse, I decided to see if I could invite his Starfleet character to visit my Klingon bridge.
It worked. And then all of my Starfleet crew whipped out Klingon weapons and jumped him. I was laughing so hard I almost didn't kick him out before he died.