Looking at what is on the minecraft wiki at the moment for 1.9, this sounds a terrible update,
e.g:
-Swords can no longer block - great
-Sheilds and stuff - I just personally think this is bad, and should be used for games combat based only
-Quiver - meh
-Possible more changes to block or entity models - fun for modders
-Subtitles - that could be good, but will be joked at(e.g. [Creeper hissing]
-New dungeon - ok

-Hm, spectral sounds similar, but also could be cool if its done well
-Redo of enderdragon boss fight - meh
Actually, after doing that list, it doesnt seem all that bad, but this new combat system could end up being absolutely awful, turning it into a bad version of Hack slash mine, and removing some core mechanics to the game.
Also I took some of these features from the "planned" list, so all may not actually happen.