So outside of the really tacky looking color...
Oddly, I wouldn't have too much of a problem with a small price increase without notice (such as 1 - 5$) but when you hike up the prices by over 50%, you really need to notify people about that so anyone who has their premium set to auto-rebill, can actually do so before they're charged with 50 dollars, thinking that they are paying 12 until they notice something off with their money. I mean, deviantart has enough bad PR since: they ignoring of the community (even the community that pays for memberships), the bad art theft journal they did, ask for opinions and then ignore said opinions, etc. This was just the straw that broke the camels back.
I mean, I get that they're running out of money... but they probably would have made more money by increasing the prices a small amount and people would have kept buying it. But instead, they increase it by 50% and are going to lose a huge chunk of people that could have otherwise afforded it.