I enjoyed the game immensely, but the biggest problem I had with it is that it definitely felt like Naughty Dog wanted to make The Last of Us 2, but were confined by it being Uncharted. As such, the game felt like it had a bit of an identity crisis. There were so many times throughout the game that I thought "wow, this level design is going to be amazing in The Last of Us 2."
Having played through the game, even though it was the longest length-wise, I was left wanting more. This is because the shootouts were genuinely lots fun (a first for the series, to be honest) and they were much more spaced out than in previous Uncharteds. Whereas in each previous Uncharted, I felt like the games overstayed their welcome in the third act with their tedious battles and bullet sponge enemies, this was not at all present in Uncharted 4. That said, TLOU was the perfect length and it never overstayed its welcome.
Honestly, even though I know people will criticize it. I genuinely enjoyed the Rafe battle. I only wish they made parry left and parry right L1 and R1 respectively instead of triangle and circle. I accidentally pressed square instead of triangle so many times.
So, in total, U4 was a very, very, very good game, but it was nowhere close to as good as The Last of Us.