Well that became an interesting debate.
The biggest points;
-We're here to play a game; it should be fun, not work.
-Background is unique to each person. Some are all about the novels, others are 'figure it out as I go.'
-GM's and Players need to talk to each other so they can reach an understanding before hand. Probably when the GM is giving the rules for the chargen session so everyone can be semi-prepared. Everybody needs to be on the same page, or at least close to it.
-If you don't give anything to the GM, don't expect anything.
Those points said, I'll give my own bit of background development story-
I like a full background if only for my own reference and taste. I really don't care if it's implemented in game or not. If it is, cool. But I'll go the extra mile and research lingo for a specific subculture, traditions, mannerisms for a character and look at subtle things to implement. etc. etc. One of my favorite examples is one of my troll street sams with a background in the UCAS Army. Initially, he was probably as cookie cutter as hundreds of others; badass, quiet, ex-special forces sniper, etc. etc. It was easy to research and play. I made this character several years ago, and I continually tweak my creations (I'm odd like that). Anyways, fast forward to now and now that I'm in the Army, I really re-imagined the character;
He wasn’t just in the Army; he was an 11B who got his Sergeant while he was involved in the Renraku Arcology incident. He’d aspired for the Tower of Power (Airborne, Special Forces, Ranger) when he initially joined, but realizations of how the Army works drove him to just grind through. In speaking to others, he was initially going to be done like most movie characters in the Army (nothing special, except maybe some R. Lee Ermey lines). Now, little things in his lingo changed. Instead of saying “I understand”, it’s replaced with “Tracking” or “Roger.” He still does PT in the morning more as a force of habit. Morning chow time is replaced by a breakfast at his favorite little diner or him sitting down with a bowl of cereal to watch reruns of the Football game he missed the other night due to his run and he couldn’t risk streaming it (actually, he didn’t want the hacker to find out and start bitching). He’s got the understanding of how the Army and similar make-up in corporations take time to maneuver. More of his Army life itself was flushed out. The story of how he got his Rover changed from getting it after he left the Army to ‘As a dumb young private, he took out a loan and got screwed by Briggs Auto Dealership- since then, he takes meticulously good care of it since he had to ‘pay so damn much for it.’’ He has little stories from when he was in the barracks or out drinking with his soldiers (actually based off a lot of stories from my friends doing the same stuff, I’m more of a homebody with my family).
I look at how the Army is changing now and try to apply that same level of changes. I can see how mages would acquire their own MOS, and probably be brought in as Officers right out the gate akin to the way certain degrees are. Deckers/Hackers actually have their own MOS now in our modern day, which makes me laugh.
Character background can make characters immensely memorable in that they can add such a life to the character over it being just ‘John playing a street samurai with a different voice’ to ‘John is Julian King.’
But the depth and level of this background seems to definitely vary by group according to their tastes.