I thought this ep was a bit uneven, I liked the opening action sequence and I thought the alien slavers story was good, it was cool to see Supergirl on an alien planet and cool to see the return of Roulette, she's a sexy villainess but damn did I want Kara to lamp her one in the mush lol.
I also really like the dynamic of Kara and Mon-El, they have a great chemistry and the humorous banter between them is fun, plus we saw some interesting seeds planted with the Dominators and those Kylo Ren looking folks that showed up at the end.
Kara's decision making in this ep was kinda silly though, I get that powers don't make the hero but her stubborn refusal to wait an hour and find a plan b kinda irritated me, she's smarter than that.
I also thought the stuff with Winn made no sense, especially Alex pretty much ignoring his concerns, comparing him to her despite him not being a field agent and dragging him to an alien planet before leaving him alone with zero protection, despite the fact he had no training, and the whole pay-off was that he got lucky with a nearby rock.
Keeping with Alex the first and last scenes with her and Maggie were nicely done and really well acted by Chyler and Floriana, but the forced drama between them is a CW staple that I don't want to see creep into the show.
I'm not quite sure how Izzy got snagged when everyone was going through the portal but I loved the sun grenade giving Kara her powers which led to the awesome shot of Kara blasting the alien fighter craft.
What power did Kara use when her eyes went orange and the alien lost his grip on Izzy? It was like she used The Force.
I dug Jo, I hope we see him pop up again on Earth.
Last but not least, I had no idea Jurgen Klopp had gotten a guest role as a villain on the show.