Lost Planet is better than Halo for a few reasons.
1. Grappling Hook
The grappling hook can be used to climb ledges or to attack enemies. On the larger enemies, you can cling to a leg or other appendage, and fire at them while they can't reach you, jumping to safety once you need to reload. (You can also throw a grenade while grappled)
2. VS
Vital Suits. They're overpowered and under-armored, but loads of fun to pilot. Most have special abilities, everything from flight to transforming into a snowmobile.
3. Taking weapons off of VS
Yep, you can take off one of the overpowered guns and fire it without a 'Suit. It's very entertaining to watch a average-sized man carry around a massive gun. These include everything from rocket launchers to gattling guns to energy weapons.
4. The multiplayer
The different modes are loads of fun, like "Capture the Egg", A unique twist on capture the flag. It should be fairly self-explanatory.
In multiplayer, there are weapons you can't acquire in the campaign (only a handful, so those without Live can still use plenty).
5. Playing as an Akrid
The alien race that plagues you in the game. Playing as them is an entirely new experience, and really shows the strength of the Akrid. Granted, you can play as the enemy in some other games, such as Halo multiplayer (play as an Elite), but they don't have this much of a difference in power.
If any of these sound interesting to you, then I highly reccommend you buy Lost Planet: Extreme Condition Colonies Edition. You'll find it a very fun experience that will keep you coming back for more.