I've barely scratched the surface but it's all kinds of cool. I've been racing around town on a road bike (fuck that San Andreas bmx bullshit) played tennis, sailed around for ages in a speedboat and done a bunch of other stuff before worrying about the main story which is looking really cool in its own right. I've done the first heist and you need to get your crew and anything else you need (I had to hijack a few different vans) before you start the heist. I'm not sure exactly how big a bearing it will have either but when you pick your crew they have certain stats and cuts they expect for being part of it. I picked a cheap crew and a bunch of stuff messed up. I might replay it with a more expensive one to see if it's any different.