I'm going to try and keep this short and sweet because Stellaris is coming out tomorrow and so I want to try and get eight more hours in before it drops (which, if video games were people, I'd feel really bad about saying - luckily they don't have the capacity to understand being snubbed.)
So, the Betrayed Hope expansion. It's fine, I guess. It's main feature is that it introduces two new game modes.
"Betrayal" has you taking over one of the solar system's planets with the intent of taking over the other seven through military force. It plays a lot like a thinly-sketched 4X (although there's no exploration to speak of, so maybe it's a 3X). In theory, this could work because The Last Federation simulates an 8-player strategy free-for-all between the alien species while you are attempting to do your thing, but I never really got the feeling that I was being allowed into the previously background simulation. My interface was almost exactly the same, and my productivity on the planets I controlled was still limited to the same old dispatch missions I'd been doing from the very beginning. As a result of this inherent time constriction, I never really felt like my power was growing as I captured planets. I suppose if you got really into The Last Federation's brand of back-seat diplomacy, it might be a refreshing change of pace to cut through the middle-man from time to time, but "betrayal" mode to me just feels like a vaguer, less satisfying version of a game I've played before.
"Invasion" mode is pretty good, though. A powerful alien has invaded one of the planets and you have to organize the other bickering 7 to drive them out, despite still having rivalries with each other and much inferior technology. It doesn't quite supplant the normal mode in my affections, but it does add a bit of urgency to the "shady mercenary uses underhanded political manipulation for peace" narrative. It would be even better if the Federation-forming mechanic were still in place and I had to occasionally sabotage a planet in order to save it, but that's nitpicking. It made me wrangle 7 fractious alien species behind the scenes and that was exactly what I wanted.
From here, I'll be going back to the base game, but I'll be upping the difficulty to normal. I may be able to get in two or more full games in my remaining time. If so, I may try a third one at hard difficulty. Here's hoping my Federation-building goes as planned.