Well that was an incredibly short lived streak. Oh well.
I finished Halo 3 today, a little over a week after getting it. This time I played on Heroic difficulty, and it was challenging but overall a fun experience. It was definitely more of the same, but that didn't bother me. There were new weapons that took some getting used to but nothing that really surprising. Story spoilers now commencing...
Storywise, the trilogy was wrapped up pretty well. There were many nice nods to the first game that made me glad to have played it instead of just jumping in to this first one. The first two games had you stopping Halo rings from firing, which would have wiped out all sentient life in the galaxy. This game finally let a ring fire, though it had a much more localized effect. You're finally able to kill a robotic being from the first and second game who alternately helps and hinders you throughout all the games. The grizzled sergeant finally meets his end. The Flood is stopped, and the Covenant defeated. Pretty much every story thread was dealt with in some fashion.
Some of the problems still remain. Backtracking still makes a few appearances, and once again there are few audio options, so it's easy to miss dialog while playing. There are subtitles during cutscenes, at least. The difficulty level fluctuated pretty wildly at times. Some areas were a breeze, even on Heroic, while some areas were incredibly tough. During these parts I got the sense that these had been designed to play through on Coop as opposed to single player. In the last third of the game there are two massive battle tanks called Scarabs that you have to take down. This took many tries and I was only able to beat it through a great stroke of luck. It would have been much easier if I had had even one person playing with me. Having a full team of four players would have been a breeze.
I'm not sure what else to say about it. It was fun, which is the most important thing. I hope that I can play through it on Coop one day, but I doubt that'll happen.