Here are a few things that I think should be added into the 1.9 update:
Sea life -
I feel that the oceans are still a bit too lonely, even with the squid. I think that there should be more aquatic animals in the oceans/lakes. These should also be the animals that you fish for. Sea plants should be added aswell, and maybe an aquatic aggressive mob?
This would make hunting alot more interesting. Deer should have regional damage(pretty much, it takes 1 hit to kill them if its a headshot with a bow, and 2 hits everywhere else). Deer should also be very fast, and run away from you if you come within a certain distance from them(so you cant just run up and hit them with a diamond sword. Hunting should be a challenge). I also feel that there should be male and female deer, and the drops should be slightly different.
More hostile mobs -
I think that there should be more hostile mobs, and the mobs should sort of vary from biome to biome.
Flying birds -
flying birds would be a very interesting thing to see in minecraft, and would be a great challenge(and alot of fun) to hunt these animals.