While some may say this game has strayed from the way Halo was meant to be played, I feel that they are mistaken. After playing the campaign four times and playing a few rounds on Firefight, I must say that this game was worth the $60 I paid for it. I have been a huge fan of the Halo universe, and this is an amazing storytelling tool. The musical direction was superb, and this was certainly a good substitution to a Halo movie. While the campaign is short, it is interesting, and if you care about the Halo lore, it is certainly fun to play it again.
And of course, after playing it, I wanted to play the original game. And that game was challenging. Even on normal! Without regenerating health, if you lost shields, you got rocked. Of course, I prefer the health pack system as opposed to the regenerating system. It adds an element of suspense and urgency. It changes your priorities around, and I think that Halo 3: ODST really scored a solid hit with the stealth element in the game. You can choose to attack a pack of enemies from behind instead of from behind. You can take them out from afar, or surprise stick a Brute from behind. The fact that shadows affect your visibility and how well you can be seen.
However, I came away from this game wanting more. I felt like it was a bit short, and that I needed more about the ODSTs. Maybe a few more missions long. Mission-wise, the game felt a bit rushed, like they were moving too quickly than they needed to.
If you liked the previous Halo games, you should like this one. However, if you thought the previous games were trash, don't waste $60 to be disappointed.