I wonder if there will be any major differences between the 2 consoles this time, they seem almost the same in features except for Kinect 2. But this is a good feature to have regardless.

Brilliant. Rumour has it that the data transfer is significantly faster than reading off the disc in xbox one and ps4. More than this gen.

Is it mandatory on ps4? Could effect performance.

Yeah its mandatory on both platforms, Sony have also shown the option to choose which part of the game you want to download first as well, i.e. SP or MP

PS4 has the same feature.

Personally I always install. I don't mind a wait if it means better, and more fluid gameplay.

We all knew this but cool. Now let them haters come here and say "ms copied it from sony" just like the way kinect tracks players wherever they are in the room instead of just "tracking the controller with just lights" and not tracking the person

Xbone, the copycat! :) "who told it first, invented it".

I wonder what internet speed you'll need for this feature. Pretty sure my 12Mbps down/ 1Mbps up won't nearly be enough for this feature on either console :/

Well, the key is that developers have to manage their data in such a way that the first parts of the game get downloaded first.  I assume that once you've downloaded the beginning stages, even those with slow speeds (including me) will be able to play them.  The problem will likely come when you play faster than the game downloads.  I hope that it results in just some kind of warning/road-block and not a crash.

Some types of games, such as open-world and perhaps fighting games, might need to DL a greater percentage than linear games before you can even start.  I still plan to download over-night whenever possible.

Or just wait for someone to start slating Sony users straight out of the bat without anyone saying a negative about it.

@OP, yep its a nice feature, and anything that speeds up the ability to just play games rather than waiting is a good thing, like resume etc. I think people have been spoiled with mobile devices where games start straight away, its nice that next gen is going that way also.