Down time aside, I'm really enjoying Star Trek Online. The beta was fun, but knowing that I actually get to keep my skill points makes it even more fun. Here are he features I really like:
Many different mission types:
The missions are so diverse that I can play for hours (or until the servers go down) without getting bored. Since I can choose from a variety of missions, I can pick the one that best suits me.
Automatic team play:
I'm not motivated enough to join a fleet, but I love that the game automatically teams up human players for missions. It makes it much more fun because we can take on enemy fleets that a solo player cannot.
There isn't any "walking around doing nothing" time. As soon as one mission ends, I can start another. And being able to transwarp to Sol is nice so I can trade in items to upgrade my ship.
The difficulty is just right for me. I die every once in a while, but not all the time. Enemy ships are powerful enough that I actually have to rotate my ship to protect weakened shields, so I'm not just sitting around and clicking. Sometimes I get down to 20% or less hull, which makes it more intense. I also think that everyone has learned to target one ship at a time.
Hopefully the server issues will be resolved soon.