meara, how noticeable is it when you wear it? If I were to wear it clipped to the front of my bra (assuming that would be a secure place for it), how well does it track movement?
I usually keep it in a pocket, but have a few times clipped it to a bra strap (where it depends on how your clothing and bra fits as to whether it's noticeable). Clipping to the front of bra is possible but I generally wear them tight enough around the band that it would be uncomfy, and clipped to a cup seems like it would show through clothes. Again, depends on clothes and wear.
I've always found it to be pretty darn accurate in terms of number of steps, but for two exceptions--oddly, it's usually fine with not believing car trips are a marathon or anything, but sometimes it thinks when I'm on a plane taking off or landing that I'm briefly running? Also, my roommate does a lot of running and finds that the distance it thinks she's gone is often off (based on her GPS run tracker watch thing), but not usually a ton (ETA: as in, she comes back from a 5.1 mile run and says the fitbit thinks she only ran 4.8 miles or something). It's interesting to see all the data, and really have it drive home how much some days I walk and some I don't. I don't use it for sleep tracking though, I couldn't find a good balance (if I set it for sensitive it thought I was up all night, if I set it for regular it though I didn't move at all)