Let's be honest here. This is probably Marvel's first failure (I thought Black Panther was not great but Michael B Jordan's character probably saved the film from being truly bad but they missed an opportunity to make his character the black panther not Boseman's who was a complete yawn).
1. Falcon / A Mackie is just boring. Character has always been the black side kick of Captain America and they couldn't give the character any more purpose or arc than simply being black. Oh yeah and Falcon is woefully impecunious... Somehow.
2. Bucky / Seb Stan is also boring. Character had nowhere to go after killing people while brainwashed and feeling bad about it, but you get 6 more episodes of that.
3. The villain is some 20ish old girl with a London accent who we are supposed to sympathise with as a 2 dimensional misguided freedom fighter type character but we don't because she comes across as a petulant teenage spoilt brat you'd expect to see do a bit part on "The Bill" or "East Enders". A bit like bhad babbie but not as bad. Just a failure from writing up to casting on that one.
4. Just missed opportunities. Highlights of the series is the "new captain america" who had a genuine villain character arc which they could have ran with to have a great villain who makes sense, but they chickened out and put him with the good guys last minute so we had to have our showdown with PG13 cash me outside instead.
The other missed opportunity was the chemistry A Mackie and Seb Stan have on screen. Neither actor really have any business carrying a series or film on their own, so this was really the show's best hope of working out. There was one scene in the second episode which was really great and we saw an exploration of a couple of moments from Captain America Civil War that could have had Starsky and Hutch type overtones. What happened to that? I'll tell you. They tried to make the series all dark and serious which just wasn't feasible with the characters and acting available (hence the old fall back on race and politics as a get-out-of-not-having anything-to-say-free-card).
There's talk of a Captain America 4 with A Mackie. If I was Marvel, I'd think twice about that.