The other half of Star Trek Online is ground combat. In true Star Trek fashion, anytime you need to beam down into a hostile situation, rather than sending Marines, you send the bridge crew.
You beam down with your officers, creating a party of 5. If you are with other players, you have less NPCs and more real players. The NPCs are pretty good. Kind of honestly, they seem to do a better job than I do, so I let them do their thing. I'm still not sure what the Science Officer is doing with tachyons in the middle of the fight, but I'll assume it's something useful.
Combat is pretty much MMO-standard with 3rd person-view and hitting buttons corresponding to abilities. The one twist is the Expose/Exploit system. About half the weapons have a special ability that has a chance of putting an enemy into an "exposed" state. The other weapons have a special Exploit ability. If you hit an Exposed target with an Exploit, the target takes massive damage, and is usually vaporized thus far.
This adds some nice coordination between characters. My Engineering officer sets people up with an Expose, and I vaporise them with an Exploit. There's a real sense of teamwork there.
An added concern is that Exploit abilities do large amounts of damage on their own, but they have a long cooldown. The cooldown is long enough that you often miss an Exposed window. So you have to decide if it's worth saving the Exploit ability for an Expose (which is not guaranteed) or if you should use it whenever it comes off cooldown.
Ground combat is okay. I don't think it's as fun as space combat, but it's interesting enough in short doses. However, I think there is a issue with skill points.
Star Trek Online gives you skill points as you play which you can invest in skills. However, Space skills are separate from Ground skills, but both use the same pool of points. Because I like space combat, I've been dumping all my skills into Space skills. This has the side effect of lowering my effectiveness in the ground game, which makes the ground game harder and less fun.
You have to make the same choice between Space and Ground skills for your officers as well. My officers have been maxing out their Space abilities, but still have poor ground abilities, which really isn't helping.
I can't help but think that it might have been better if there had been separate point pools for Space and Ground. Or if each skill had both a ground effect and a space effect. That way you don't end up gimping yourself for one half of the game.
Not to mention that there are no respecs yet, and if Cryptic follows the Champions Online pattern, skill respecs will end up being sold in the RMT store for real cash.
Well, that's an overview of Ground Combat and the Skill system. I think that they are both interesting yet flawed elements of the game.