First, the movie was never about dealing with grief. It's quite the opposite. The movie is all about enjoying life to the fullest with the people we cherish.
Second, people said that the quirky and goofy interactions were played for longer than they should. It's the point. In order to live our life to the fullest, we most learn how to enjoy these small moments and act as if we're gonna die tomorrow. Otherwise, the inevitable tragedy of losing our beloved ones will leave even a bigger scar, because of our inactions and guilt. After finishing the movie, you'll realise that all these silly interactions and the lessons learned along the way were the highlights of Haruki's life.
Third, another critique that comes often is about our main male lead. He comes across and act as the cold and antisocial guy for a long portion of the movie. This characterisation of him was genius. He's acting like everyone of us probably right now. What's the last time you've checked on your mother, father, sibling, friend... We all have these moments when we all lose sight of our close ones in the search of some material and fleeting satisfactions. And the movie hammers this point down.
Fourth, some people criticize the plot and deem it superfluous as we knew that Sakura will die from the first seconds of the movies. Nothing can be more wrong. The plot shows us that even if we all know that everyone who's close to us is dying, we as humans, will either be willfully blind to them and to their needs by not giving them the time they need. Or by dwelling in these negative emotions instead of enjoying these moments with them to the fullest. These moments were you and your lived ones are alive.
Minor spoilers: not related the plot.
Sakura's mask of the strong girl who doesn't fear death is the mask that everyone of us is wearing all the time. Your beloved oneq may seem okay on the surface and may greet you always with a smile. But it's maybe time to check on them and uncover the dragon beneath. And for me the moment when the mask unveils was one the high nots and most memorable moments.
Artistically the movie is gorgeous with some emphasis on symbolism like with the names of our two leads. And I'm sure that by watching the movie for the second time a lot of lessons would be uncovered.
I couldn't help, during the entirety of the movie, but to see Aerith and Cloud in Sakura and Haruki. Their starting point, dynamic and fate is all the same. The thing that ties to the main theme of enjoying life with the people we love.
