I haven't had much of an issue with MCU costumes for the most part. I think the movie costumes generally are quite good. And for the most part, I'm okay with the television costuming, even if some of it is too muted, like Daredevil or limited by imagination or budget like the Inhumans and Deathlok on Agents of Shield. I've been impressed with how much money they put into these Disney Plus series and it looked to me like Loki had the biggest budget of them all so far.
As for Loki, if I hadn't known there was a second season before looking at the first season finale I would have a harsher opinion of the finale. It spent a lot of time introducing Jonathan Majors' character and setting up his backstory. I wasn't expecting them to actually have Majors in the series at all, because I was thinking that Feige would want to wait to introduce him on the big screen. However, with the idea of this Kang being a variant it gives them a lot of leeway to introduce various versions of the character in other movies or series.
To be honest, I wasn't that impressed with Majors in the finale, similarly to how I felt about JLD in Falcon & Winter Soldier. It was a subversion of expectations to have this variant, who was unthreatening and a bit goofy, be the 'big bad', and while that might work for some, it didn't for me.
I've seen a fan theory that the person behind the TVA should've been another Loki and I would've been fine with that, or even Gugu Mbatha-Raw's character, and they hold off on Kang until later.
As for the season itself, it started intriguing but bogged down in the middle, not unlike the other Disney Plus series, though F/WS rebounded the quickest and the best, then Loki, while WandaVision fell off a cliff. The planet with all the Lokis didn't turn out to be as fun as it had to look on paper. A lot of the season also rode on how you feel about Sylvie and I was just okay with her. I didn't hate the character, but I didn't love her either. Her reveal was a bit underwhelming because I was expecting more of a name actress, someone like Vanessa Kirby (Mission Impossible, Hobbs & Shaw, etc.). Also the weird, almost incestuous kind of relationship between Loki and Sylvie didn't work for me. And I felt the series too quickly turned this Loki from villain to anti-hero to genuine hero and I wish they had kept some of his edge, some of his ambiguity.
Right now, I'm not as thrilled with Kang as I was with that end credit scene for Avengers. The good thing is we might get to see Majors doing various versions and perhaps when the 'real' Kang shows up he'll have that menace I'm looking for.