Fairly shocked there were people here saying the Crimson Fleet storyline is good, or even the best in the game. It's laughably terrible.
-The only way to join is to get a UC bounty or do a favor for them, then get offered the undercover mission. This could be interesting as an option for a good character to experience the plotline, but it's the only way for any character even if you want to be a bad guy.
-There's no option to come clean to the CF and ditch the UC or otherwise become a double agent until the very last mission. If you act too much like a pirate during the missions it will fail the entire questline, even though the CF wouldn't care.
-There are random missions where you steal something, hijack ships, or smuggle cargo. But that's the only "pirate" activity you do. The first story mission is a dungeon crawl, the second is a dialogue mission where you talk to people. So you join the pirates and barely do anything remotely pirate-y.
-After every story mission you fly straight back to the UC and report in. Never mind that any CF member could easily follow you and blow your cover, you can bring a Crimson Fleet companion to the UC and not suffer any consequences. If you're trying to sell me on this undercover BS plot, not letting me BRING CRIMINALS TO A UC COMMAND SHIP is pretty basic.
-Every mission has an oh-so-convenient way to avoid having to do anything evil. There's no scene like "shoot this UC cadet in the face or we'll space you."
-The whole story is just a treasure hunt and the reward is money, no cool ships or pirate stuff. Lame.
1/5, very disappoint, I'm going to finish the main quest for completionism OCD and uninstall.