A very good sequel for the legendary classic ; underrated due its time of release
However for a newcomer to the series you better go directly to the Halo 3 & ODST which unfortunately are only on the Xbox 360 :( as they are more compatible with today graphics & Audio levels
The difficulty level is higher than Halo1 , however some very good features is making it even more playable like holding 2 guns at the same time, the way you handle vehicles is enhanced, your allies are smarter; etc.
In brief the game is super fun & very much underrated; and definitely if it was released on PC at least half year before its actual release time, it would have rated much higher
Graphics: 8.5
Audio: 7.5
Gameplay: 9.5