An important thing to know about the other "faction" within STO is that, well they're different.
Klingons are a separate faction but not in the traditional sense. Everyone is required to level a Federation character for a while before acquiring the ability to create a Klingon character. You don't have to complete a quest or anything special, just hit up your character creator again once you've reached level six with your first Feddie character.
The Klingons are heavily PvP focused. Expect to be engaging other players in order to progress about 90% of the time. Future content is likely on the way but right now the life of a Klingon warrior (they're very much about honor and dying in battle, just in case you weren't aware) is to find other players on the Federation side and blast them into space debris. While not everyone in STO is happy about this move, the gameplay is still fun enough that having a Klingon character is worthwhile. You can fight in ground or space battles, instanced or more open warfare and even against other Klingon players.
Just remember: This faction is fairly lacking in the PvE department.
And what's the game like beyond those first five or ten hours? I haven't gotten too far past that point, yet, but there's plenty to see. You'll encounter all kinds of alien threats and allies, as well as what STO calls "Episodic Missions" which -- counter to how they sound -- aren't pieces of the game you buy separately.
Episodes are named because of the television series. When you play an Episode Mission, it's like you're playing an episode of the shows themselves. These missions are really fun, because they take you on a journey through both space and storyline. There's a really fun one early on, although right now they're sprinkled around the game and aren't meant to be the only way you level.
Other mission types ask you to patrol sectors of space. This can get old fast, so if you do play I recommend doing these sparingly. You can also explore unknown space, which can result in conflict of varying types. Sometimes you'll fight in space, sometimes on ground -- other time you'll need to investigate a planet or area of space. That last one can sometimes be less than ideal, as you'll literally need to find "Five of X" much like in other games.
There's also Fleet Actions and PvP, though. You can progress through PvP, which is nice if you're looking to mix things up a bit while still gaining ground.
And why do you want to level? Well, your captain and Bridge Officers (the guys who teleport down to planets with you, when you're without friends to play with) can all equip all sorts of gear from weapons to personal shields and armor. This stuff will show up on both you and your Bridge Officers and like all MMO gear it'll look increasingly cool as you move through the game's content. There's also a really cool trickle-down effect when you get new gear. Obviously, you're going to put that shiny new stuff on you, the Captain, but the stuff you had before can go to your lackeys.
Hooray, it's like getting double the loot!
Your massive space ship can use gear as well, although gear won't change the look of your ship -- just the performance. The look of a ship is altered through a very in-depth customization system, and parts are given up front. You'll likely spend a good chunk of time fiddling with the look of each new ship class you get.
I know that's a lot to take in, but don't feel like STO is the same way. Sure, it's different in some ways, but it's also similar to other MMOs as well. The tutorial does a decent job of teaching you the essentials -- even if it's a bit chaotic in places. If you do give the game a try, be sure to read our seven newbie tips and last week's guide on the game's community. Also, come back each week for more Captain's Log installments!