I know the movie aired 15 months ago but I just watched it two days ago.
And I loved it!
However, as I am not too good with reviews unless rage is involved, often just redirecting others to identical sentiments made by better review-writers, I quote user huangtianci from IMDb [parentheses are mine]:
Melancholic yet hopeful
I love this movie!
Despite the recent controversy about gay issues in Thailand, this movie is not focused only on gay romances, [or even being "gay"] but love in general.
In the movie, we witness various types of people's relationships and the acts of love they do to each other, whether they are of mother and son, brother and sister, grandmother and grandson, husband and wife, or the love among friends.
'As long as there's love, there's hope'. This sentence is from one of the film's theme songs (which are mostly written by the director-writer himself [and sung by both him and Witwisit]), and it exactly presents the tone of the movie: heartwarming and hopeful.
While being promoted as a movie about love, 'Rak haeng Siam' is also one of the best family and coming of age movies ever made. We can see how the characters have to cope with their past losses, and how they overcome their grief. The teenagers have found who they really are, what they want, and go on with their lives. These serious topics are delicately presented, [like a drama minus the stress] thanks to the director who brilliantly helms the movie.
All the main cast are at their best, especially veteran Sinjai Plengpanit, as a woman who's desperate to save her family from being torn apart. Her performance is heartbreaking. Another praise for newcomers Witwisit Hirunwongkul and Mario Maurer, who play the major teenage roles. They are so into the characters we could believe this is real.
'Rak haeng Siam' is indeed a good film as many have said. It tells us even though our love is unanswered, we can still learn from it, and we should be grateful that, at least, we are once capable of loving.