I have made beers with and without it. I will say it helps on clearing the beer if that is important to you, it also helps with chill haze as it takes out a lot of proteins.
Some of my lighter beers I like to brew and give to friends and tell them the label floated away in bleached ice water (some of my friends believe anything), and if they can tell what type of beer it is.
With Irish Moss I actually get some surprising BMC answers. They are shocked when I tell them its homebrew.
In Primary: Belgium Chimay clones.
In Secondary: Braggot, pale ale, end of the world white.
Conditioning: Mead, Cider, braggot, Belgium Wheat.
On Tap: Clones, Chimay Blue, Red, Porter, malted cider.
Bottles: Far, far, too many to list.