Mine turned up today (thanks Tesco) and I've managed to squeeze in an hour or two. The gameplay is exactly like it used to be (oh, the happy memories) with some nice tweaks (e.g. no more hyper accurate pistol-sniping). The general feel of the landscapes is much richer. The ability to switch back and forth between the old and the new looks is nice. I found myself on several occasions just stopping to admire the scenery.
I have't even reached the Flood yet. I remember when I originally played that section, that when I started going into rooms covered in purple blood (that I didn't spill) that the hairs on the back of my neck stood up. Time to see if that can be recaptured.
I must say though that some of the human facial features and movement styles are still very old-Xbox. Nowehere near as refined as, for example, Reach. However, rose-tinted glasses or not, I choose to see that as a fond reminder of the original version.
All in all, I'm happy with my money spent. Now all I have to do is remember to actually get some sleep tonight.
Oh, and by the way, my pack came with the Grunt Funeral Skull code, avatar codes for male and female Master Chief suits, Halo Reach multiplayer maps and 2 days free Gold membership.