I have the 820 as previously posted. With having time off work and having a 'new toy' I was battering it
Now back at work the phone is consuming around 60% only. Moderate use at work (occasional text, call, email, surf), heavy use for a good 3-4 hours after work (same stuff but more). Live tiles and pushes for a handful+ of apps. Needless to say, overall really happy.
And on thread subject, I've witnessed no loose battery at all and there is no noise/rocking.
Only thing I'm slightly disappointed with is camera flash now. Seems very weak. Faces/items near the phone get lit but flash seems useless when say trying to light up a corner of a dark room. Ar' well.