Honestly I wish this would be done for more games, as it is starting to in some forms (3DS versions of old N64 games. Its not great, but its a start...).
Upping the graphics and possibly tweaking out a couple of bugs so that an old game with great gameplay can stand with the new games coming in in terms of technology? A great idea. There are so many old games I love playing, but have to stop doing so after a couple of hours because the extremely poor graphic quality gets to me. Halo doesn't really have this problem, but its on its way there.
To all the people saying 'I want extra content too' that makes no sense. Despite destroying the story continuity in some cases, you would be changing the reason this is being made. It is not a sequel to the Halo franchise, that is what Halo 4 is. It is the original Halo in its own glory being revamped to today's graphical standards. The AI was good enough, play on the highest difficulty and tell me its a cakewalk. There may be tricks and exploits that let you get past easily, but that's the fun of using them. If you don't want that to be there, simply don't use them and try and win without it. I know a number of people will be able to do this, and quite probably easily, but many more will not. In addition, according to one of the posts on the first page, there is some minor new content involving skulls and story involving 343 guilty spark through video terminals, which is really about all that should be done. Skulls are for fun muck around things IMO, and a story for 343 guilty spark wouldn't go astray, and probably wouldn't interfere too much with the rest of the story.