You will all be
surprised at how well he portrays Han Solo. Brilliant under the radar casting choice.
I am you and what I see is me.
I don't think people are so much criticizing Alden or his acting, but more along the lines of not liking Disney for deciding to make a "young" Han Solo standalone film.
People will always see Harrison Ford as Han Solo because well, he is that character. It's not like he was in his 60s or early 70s when he filmed A New Hope, he was 33. We already know Han's end game, he was in 4 films where he was young and old. It's not the same like it was casting a younger Obi-Wan for the films. More books (that are canon now, unlike the older Han EU books) or comics would have been better suited for this character.
There is plenty of source material in the SW Universe they could have touched on, like them deciding on a Boba Fett spinoff seems to have more agreement with fans than a Han Solo film.
Disney would have been better off not doing a Han Solo spinoff but maybe even deciding on an Obi-Wan film about anything that happens between Ep3 and Ep4 using Ewan, since he played a younger him in the prequels.