Summed up version:
It's a rogue-type game, so if it's your type of game, go for it. Be warned, it's a very hard game if you don't know what you're doing.
FTL: Faster Than Light is a very amusing (in my opinion) rogue game. You're using one of 20-ish ships (all but 1 has to be unlocked in a variety of ways) and your goal is to beat the enemies. Summed up.
There's a variety of aliens you can use (one is unique to Advanced Edition, I might add), all with various benefits.
Each ship is unique - no two ships got the same playstyle (even though one might think so).
It's very hard to find a ship that's 'perfect' (unless you get a Weapon Pre-Igniter, which lets you fire all your weapons the instance you jump to a fight) as all of them got their own flaws.
Some ships lacks sensors, meaning you can't see your own ship layout, except the rooms you have crew in (if you have Slug crew members, you can see the room next to them, too).
Another ship lacks doors, meaning that if there's a fire, you'll have to move your crew to that room to put it out.
Some ships lacks shields but gets something else instead in terms of defense, like a Super Shield (blocks up to 5 damage of any kind but takes double damage from Ion weapons) or the Cloaking system (which gives you +60% evasion for up to 15 seconds but if you fire during the cloak, you'll drain some of the cloak time).
All ships focuses on various things:
Some focus on dog-fights (a.k.a ship vs ship)
Other ships relies on drones for repairing or attacking
A few ships (3 from the top of my head) focuses on a special weapon that got a VERY long charge up time (50 seconds at level 1, ouch!) but deals a lot of damage instead.
And finally, my favorite kind of ship: the boarding type. Killing enemies by boarding is high risk-high reward.
If you manage to pull it off, you get better rewards than if you kill them by destroying their ship but if the enemy has a medbay, it might be troublesome to do so.
I might add, some ships doesn't even START with weapons.
They rely either on their special weapon OR on boarding.
Now, to add insult to the injury, some ships are literally impossible to board (either due to the Super Shield which prevents it or the fact that they are Scouts, meaning they have no Oxygen system).
Should that let you down?
Keep at it and defeat those damned Rebels once and for all, people!