I pretty much agree with what you said. This show at first didn't strike me as being all to great, probably because I'm not that into the Green Lanterns, but the second half of this season just blew me way. At first I didn't like the look of the series but now I have to admit at least the space scenes really look great. I really feel this show as grown and proven it self as being a very good show. It's really too bad we'll never get to see the Sinestro Corps (war), the Blackest Night, John Stewart, Kyle Rayner or any of the other things we'd all love to see.
I like how Aya was shown to still have respect for organic live and only destroyed star systems that were uninhabited, so she only really killed one person while being not herself, that's still terrible but not as bad. I really hoped for some cheesy ending to save her after she did the virus thing but it seems the show knew a better way to end this season. I'm really bummed we'll never get to see the Blue Lantern Razor but I really do like how he will become a blue lantern by believing in Aya still being out there somewhere.
I'm pretty sure if DC would release a comic featuring Aya and Razor I'd get it even though I'm not getting any of their GL related titles at the moment. I just really love those two characters and hope we'll get to see them again in the future.