Uhg, the people losing their powers hing is such a lame cop-out. I hated back in Flame of Recca and I still hate it now. (Worse it seems like a double cop-out because we have already seen a number of adults with powers)
Medeka's complete change of personality was also a bit jarring, I feel like it was working way too hard to make a point(or add a 0th hour moral to everything), I wish they had just left her like she was... or something. Honestly it feel bizzare. Zen doesn't change in the slightest but Medeka makes a 180. It feels the it should have been the oppisite, Medeka owing to her nearly inhuman nature has perhaps grown in wisdom and understanding but is mostly the same, but Zen having grown and matured (and perhaps a bit more world weary) finds himself no longer able (or willing) to keep Medaka's pace decides that while he'll always love Medaka, he's no longer the same person he was ten years ago and they end up parting way. Oh well, somehing like that would be a lot more bittersweet, but would feel truer to the characters, in my mind atleast.
I dunno, having Medaka mature into just a normal women feels so bizzare... Her parents aren't normal and we see many other who lack that pedigree who aren't normal as well... Bleh, feel like I'm repeating myself but it feels like some sort of forced 0th hour aseop about how people may seem super human as a teenager but they all just become normal adults... or something.
(( Seriously though, wtf is the flask plan then? Did the flask plan girl grow up to be normal? Wasn't Zen part of the flask plan why did he just mature into a normal adult? Argh, I'll just file this along with Death Note for endings that make no god damn sense. ))