Like alot of us on these boards I would assume, I have experience using both a block/guard button as well as holding back to block. The truth is both have their advantages and disadvantages. However both tend to work well for the games they have been implemented in.
It is difficult to imagine a game like Street Fighter using a block button, its equally difficult to imagine a game like Mortal Kombat using back to block.
Having used both, in terms of which one I like best I would probably give a slight nod to the block button for only one reason. It lets me choose whether I want to block or not. When using back to block, block obviously shares the same directional command as back. Whether you get "back" or "block" is triggered by whether your opponent is attacking you and if hes not attacking you, then you walk back. The game makes that determination for you.
In a game with a block button, the player controls whether hes going to block or not. This makes things like walking backward while your opponent whiffs an attack and then counter attacking easier. I get to make the choice myself rather than have the game do it for me.
Thats just one example though. A block button also has its share of disadvantages as well. Just as holding back to block has its share of advantages.
I cant speak to whether holding back to block will be good for Injustice because just knowing that alone isnt enough to give me anything. Its only one mechanic amongst many and how it works will depend on how all the other mechanics work with it.
But the system itself isnt new or shocking. Holding back to block has been around since the beginning of fighting games and is actually the mainstream, whereas we MK players are the oddballs who like having a button to block lol.
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