It was sad. It gives you the idea they will never meet so nothing good about it AT ALL.
eh? are you not seeing it a bit too dark. considering the girl at the end told exactly that story and the younger brother has now become the swim teacher... they are going to meet again, but the outcome is unclear.
I think you missed something in the last picture... he is floating in the pool right? and the old guy shouts at somebody... I think he ist schouting at the girl...in the last panel you see him floating and at the lower right part there is a hand... so I think that that is HER hand... ;-)
the story is good! It was sad but not sad too. How do I put it... The ending is just good although it doesn't give us more detail about what happen next. Still, this is a great story!