Xander being blinded in one eye was done purely to 'surprise' the audience, and is the worst creative decision Joss Whedon ever made, so I stand by my opinion.
The iZombie writers were on a roll last night, only to go and shoot themselves in the foot with a completely unnecessary 'twist' that did way more harm than good.
I'm so dissatisfied with what went down that I may never watch this episode again.
But . . . but . . . it had talking cartoon devils and astronaut-brain sushi. What's not to love?

And I've got to ask: What was so awful about Xander losing an eye? Not that I have strong feelings on the subject, but I wasn't aware that that was considered a big mistake or even all that controversial, let alone the worst thing Whedon had ever done. I see much more people arguing about the Spike/Buffy relationship or complaining about the "Bad Beer" episode.
Personally, I thought ruining Xander's and Anya's wedding was a mistake. The eye thing . . . not so much. (Especially since the series was almost over at that point anyway, so it's not like Nicholas Brendon was going to have to wear an eyepatch for another three years or so.)