I’m not sure if it is the right place to post this. I know some of these are likely to be just unimplemented features, if that’s the case just dismiss them.
-Blocks have no tooltips or easy ways to identify them.
-Many blocks are using debug textures.
-Mined blocks do not always immediately disappear but you can walk though them. Doing so allows you to see through walls.
-Long delay (lag?) before blocks are placed.
-Torches can only be placed on the floor.
-Player tags can be seen from any distance and through surfaces.
-Torches can be placed underwater. When you do, the water block it is placed in disappears.
-No models for players; they are shown as a big orange block.
-No models for tools (shovel, axe, pickaxe). No inventory icon, just what seems to be placeholders.
-Noticeable stuttering when moving, even with minimal graphic settings.
-Tree leaves stay in midair after trunk is cut off. This might be annoying aesthetically.
-Surfaces of land flash rapidly when viewed from certain angles.
Specs:
CPU: Intel Core i7-3770 @ 3.4GHz
GPU: GeForce GTX 780 (driver v340.52)
Memory: 8GB
Resolution: 1920×1080, 60Hz
Monitors: 2 x 1920×1080 60Hz monitors
Browser: Chrome 36.0.1985.125 m