Excellent balance of difficulties for campaign, as well as a fitting conclusion and good replay value.
Into the second level, and the story starts to develop. When I finally relieved by numb butt and got up, it was (ashamedly) half twelve. Time to get some shut-eye. By then the game had really started hotting up. The new scarab battles are great the way they are a platform you can stand on, and then blow up. That's something you don't see enough on videogames. Nothing beats jumping off a scarab just in time, and having everything around you lit up by a blue explosion, landing on the ground and turning around to admire the scene of destruction before you.
At this point in time I had not touched multiplayer, for fear of someone discussing the ending, but when I had finished the campaign, I was quite impressed at the maps and the sniping spots already being appreciated on them. There are some truly skilful players on there, and I felt slightly out of my depth (I only beat them by a margin of several kills!). The additions in single player are also good. The vehicles were exceedingly fun to drive and it was nice to see a flyable UNSC vehicle. Online co-op, although I haven't yet tried it, promises to be fun. However, the weapons are somewhat disappointing. Most of the added ones are support weapons, and the assault rifle can be outclassed by the battle rifle if you are good enough to land every shot on target. Perhaps the only weapon that doesn't deserve this is the brute spiker, but then it only really shines when duel wielded.
The only letdowns were Forge and and the camera used to watch replays in the Theatre. The camera moves slowly, and when you thrust, it is too hard to control. In Forge, you may only spawn items, not fiddle with the geographics of the map as would have been much more satisfying and made for some truly great mongoose chases.
Overall, this is a great game, an effective end to the trilogy and, although it's a cliche by now, a worthy addition to the series. Unfortunately the fact that Bungie sensibly "stayed to the winning formula" and didn't remake the game has led to a few fans somehow being disappointed. It also relies on people having played Halo CE and Halo 2, which a few of my friends have not, meaning they don't get what all the buzz is about. However, from my point of view, this is a fantastic piece of work, and I wish Bungie all the luck in the future!