I saw it on release night and was not particularly impressed. In my estimation, there are three main issues with this film.
1. They've not been able to properly patch over the trouble production.
The film essentially has one pace, being that stuff sort of happens at a middling speed. It's not really slow enough paced to be outright boring, it's not quick enough paced to be a rush.
In terms of tone at times the film was entirely schizophrenic. For example, the Kessel scenes literally juxtapose incredibly cruel treatment of Wookie slaves with slapstick humour droid uprising scenes shot by shot.
It comes across entirely as what it is - a film worked on by two different teams with two very different creative visions that was in the end cobbled together and rushed out the door when in an ideal world either a) more time and budget would have been given to Ron Howard, or even better b) Lucasfilm would have chosen the initial creative team better.
2. There's no real journey.
This probably relates to the troubled production mentioned above, but you don't ever see Han develop as a character through this film. He begins as a streetwise snarky criminal who yearns for bigger things and trusts no one except those close to him (Q'ira, at that time). He ends the film as a streetwise snarky criminal who yearns for bigger things and trusts no one except those close to him (Chewbacca).
The one character who does seem to have an interesting journey, being Q'ira who went from a seemingly wide eyed urchin to an organised crime lietenant, has any explanation of this journey hand waved away about 4 or 5 times throughout the film. All we hear is that she's done terrible things that she doesn't want to talk about. Then she betrays Han.
3. It was not a particularly ambitious film.
I don't want to come over all RedLetterMedia, but at times it did feel like a bit of a box ticking exercise for Han and Chewie background lore. Han meets Chewie, Han gets his DL-44, Han meets Lando, Han has some kind of falling out with Lando, Han gets the Falcon, Han makes the Kessel Run, Han ends up working for gangesters.
It doesn't push any envelopes - it doesn't present Star Wars in a way that we've never seen before on the big screen like Rogue One did, and it doesn't develop the core mythology of the franchise or have a strong message like The Last Jedi did.
In that way Solo is probably most comparable to The Force Awakens, which was by comparison an incredibly slick production, the release of which was in an entirely different context to the release of Solo.
In conclusion, I thought it was the worst of the four films that have been released since the Disney takeover.
There were a lot of things about it that I did like, but compared to the above they're all superficial bits and bobs. I enjoyed the links to the Clone Wars and Rebels television shows, as well as the wider Canon and Legends lore. I continue to enjoy the commitment to using practical effects and real props and sets in the Disney era Star Wars films. I thought the actors were all actually decent, especially Alden Ehrenreich who I thought did a very very good job.
Oh, and as for THAT cameo - despite my above comments about enjoying the link to the lore, it felt needless and gratuitous. It was to me at about the level of Jyn/Cassian running into Dr Ezavan and Ponda Baba in Jedha City in Rogue One. Not a fan.