The gems seem rather pointless. Not in the sense that they don't do anything, but that they shouldn't be needed at all. That's my only complaint with the game (other than the diagonals).
The game has been beautifully simplified. I find that this allows the player to rely a lot less on execution and more on reading their opponent and reacting. I mean, you can string together auto-combos with lp-mp-hp, or you can press lp+hk and deplete a meter to perform another. Launching and juggling is way more fun than it has any right to be, imo, and it's not as strict as you'd probably think it is. It really is fun, and for as simple as it is, it's still deep and fun.