Yea I hate, HATE asa, It should of ended with Primlua! well that would of been the best ending for me, but still if it ending with Nerine,Sia or Kaede it would of been better. I agree 100% with Asa was better as a supporting character. I hated how they showed her saying stuff like "I like things that best how they are now" with being friends, but still she kept on going after Rin, behind Kaedes back, Asa knew Kaede loved Rin and she was a really! good friend to Kaede at the start of the show, but she was Backstabing Kaede but going out with Rin, while not telling kaede anything!, UNTIL Rin basically tell's her he likes her best :/ Asa is the Worst type of friend you could have. Primula was kind to kaede and tried to help her out, and Nerine and Sia were alright too. Rin also was a bit of a Idoit the way he treated Kaede, and even Primula who alot of people forget.
Though I dont think the ending was really! really! bad since, it still ends in a open-harem ending way, we all know Rin is with Asa, but to be honest I dont think it would last. All the girls are still after Rin, So even though at the end of the show it ends with Asa, it doesn't make me think that thats how things will always be. With Da Capo (Season 1 and 2) it ends with Nemu and its a Concrete ending, which would never change after the show, but with Shuffle, I get the impression anything cabn happen.