Sorry for two posts in a row.
I still have that problem. Tried restarting steam, like OP, cache, complete restart, reverting back to 1.04 (runs smoothly) - but with this beta patch the game starts and immediately shuts down. No crashlogs, no nothing.
If it helps, I use
Mac OS X, 10.10.3
3,4 GHz Intel Core i7
16 GB 1333 MHz DDR3
NVIDIA GeForce GTX 680MX 2048 MB
EDIT:
I looked into the content and tried to run it from there. My terminal gives me this:
NameiMac:~ Name$ /Users/Name/Library/Application\ Support/Steam/steamapps/common/Pillars\ of\ Eternity/PillarsOfEternity.app/Contents/MacOS/PillarsOfEternity ; exit;
Failed to locate data folder
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