Company with friends enhances it by about 150% I'd always say. Win or loss, doesn't really matter. In the end, if you play enough you begin to improve in skill level. I can attest to this for the few online games I play. Then again, I prefer the co-operative games rather than pitting you against pros all the time. The attitudes of people really vary from game-to-game.
I guess that covers the "Gaming experience may change online" label you see all of the time. Mostly these days I play Monster Hunter 4 Ultimate. A whole different bunch of people. It's hard to have a bad experience when you're constantly working as a team and celebrating your victory. There's probably a whole lot of psychology and reinforcement that goes into it, regardless. Depends really what audience you're expecting to play with.