What's the deal with your reputation level? What's the point of it?

You get upgrades to your safe houses, ammo piles, vehicle, upgrade to vehicle weapon. NPCs in the towns react different in what they say to you too, when you stand right next to them for a bit they'll push you away at first but with higher rep they'll walk away or say things like "don't want no trouble, man" and other stuff.

 Oh wow, I had no idea all that was handled by your rep, thanks, was really wondering what the hell the meaning of it was.

I'd better clear something up about my previous post before someone else corrects me:

It's your buddies that upgrade your safe houses. However, those upgrades seemed to me to go hand in hand with your rep level which goes up after completing story missions. To get the safe houses to upgrade in line with that though you should follow the buddy route to doing those missions. As far as I could tell, simply doing the buddy side missions you get at the bars would give me a "Reputation Increased" message but not actually increase it to the next level or give me safe house upgrades.

So, in short, buddy route on story missions means fastest way to increased rep and safe houses.