Using halogen gas in light bulbs has a couple important effects that are useful.
Halogen bulbs last longer than standard bulbs.
The filament actually gets repaired over time, and since a broken filament is the ultimate reason a light bulb burns out, this prolongs the life considerably. Not having to change your bulbs as often qualifies as a nice benefit, while saving money by not having to buy lots of replacement bulbs is always great.
A halogen light bulb will burn brighter than standard bulbs.
If you typically use several bulbs to light a room, chances are you could end up using one or two fewer bulbs to get the same amount of light—which can actually translate into energy savings as well. Bright light is a great way to get everyone in a great mood.
Halogen light bulbs emit a whiter light.
The whiter light provides a more appealing, brighter feeling as well, and renders color even better than a standard light bulb. Your room will look less like a dungeon and more like an appealing living space.