I think this film is a perfect example of one of those times when a film can be good but its just not what the audience wants to go see at that point in time. Sometimes you can produce a good film, do your best at marketing it and it just doesn't connect with audiences.It unfortunately for many came with a shit load of expectation, the weight of the SW franchise, mixed thoughts on TLJ and a lot of armchair critics thinking they could do better than the entire management of Lucasfilm just because they've watched Empire 200 times and were aware that their was some directorial issues
As a film in itself, it's pretty damn good. I enjoyed it at least. For me the original SW films were very enjoyable throwaway romps that grew and people gave them a weight that I don't think was initially there.
Take the current MCU. Some are huge fucking end of the world Infinity Wars. Some are Ant Man, light and breezy. Solo to me was Ant Man like, and I enjoyed strolling through their universe as opposed to being beaten over the head with ultimate good Vs Evil galactic stake pieces
In general people just didn't seem that interested in watching a story about young Han Solo. I still think they should have done a Lando focused story, ending with the hours before Empire when he makes his famous deal. This might have worked as the character had much less of a focus in the original trilogy and hasn't been in the new one at all, wheras people probably felt that Han's story was done.