These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ho Yay: Natch, seeing as it's a book about two legendary lovers.
Tear Jerker: The whole thing, if you know the ending. It's one of those stories that you'll read once for the beautiful writing and characterisation, but never again because the ending will rip out your heart and paint pictures with your aeortal blood.
Wimpification: For the most part the characterisation is pretty awesome, but once on the field of Troy Patroclus becomes the Non-Action Guy, which rankles pretty hard for a fan of The Iliad. The worst part is when his Crowning Moment of Awesome - pursuing the Trojan forces from the burning ships all the way to the walls of Troy, cutting down many great Trojan heroes on his way including a son of Zeus - is portrayed as something wildly out of character that he would normally be far too meek and gentle to accomplish without some kind of divine help.
Possibly a Double Subversion, as despite Patroclus being far less of a warrior, he's still a Badass Pacifist and Determinator par excellence and is specifically stated to be copying what he saw Achilles do for almost 20 years.