I've now spent several hours with the alpha and I must say I am loving it. In fact, I went and pre-ordered the digital copy from the PSN store just now.
The graphics are gorgeous, although a bit uneven at times, it's still stunning. The PvP level on the Moon is jaw dropping. I literally ran around and looked at the environment and took tons of screenshots because I couldn't stop myself.
The game feels very polished for an alpha and I only encountered one bug.
The difficulty level is perfection. I can't remember the last time I was this challenged by a game and actually had to play seriously and not just run in front of everything and killing it and the instantly regenerating health. Bungie know difficulty for sure and I will be gaming on the highest one to get an even longer game. Very excited.
I love the social city, and I hope that there will be more in the future. The interaction system with the players is also good for consoles R3 + Options to inspect and add friend etc. It's very smooth. I really get the feel that this is somewhat of an MMO, even though I only played with like 6 people tops once in the open battlefield to kill the giant Devil, which is nice, because I tried Wildstar and its repetitiveness killed it for me, this is fresh and new and I am liking it.
The the soundtrack is godlike. But that was to be expected after the Halo games, nothing shocking. However, the sound effects from the blasters I feel are a tad weak and could be a bit better, but not bad by any means. I guess I am spoiled by Battlefield's level.
I like the menu system, even though it took me a while to get used to it. Feels like it'd be ideal for a mouse, though. But it works and I can't complain. Very clean. And the fact that it starts counting down from 3 instead of 5 is wonderful.
But boy, it sure does feel weird playing an FPS game on console again. I think the last one was Halo: Reach for me, so it will take time. I am so used to PC at the moment.