I had to return my first fitbit scale because my firewall blocked the first outbound request that the scale made (it was a new unidentified device on the network), which caused the scale to brick itself.
If the first registration request fails it does not appear to retry. Taking out the batteries had no effect.
I was stunned they hadn't caught this in product testing. Not that the first request could get blocked by an anal firewall but that a sporadic internet connection doesn't cause the device to brick.
With that said, I've become less happy with their hardware over time. My One frequently resets its clock and thus miscounts steps; my Aria downgrades my network to 802.11b (but that might be fixed by getting a better router?).
Edit: to clarify when you go to fitbit's website and you go to the device's settings it shows you all of the measurements and lets you delete some. If it has been extracted to a fitbit account then it is "saved" (testing exporting my fitbit account it does have my old weights), but for example all of the measurements of our cat+me which did not have a fitbit account were auto deleted after some time period. I wonder if you don't log into your fitbit account in less than 90 days if you would also start losing your weight history or something similar :\ Either way deleting weight data on a product whos sole purpose is keeping track of data for you is sad.
It also took Fitbit over a quarter to launch Strava integration after announcing it, yet that feature is probably a couple days (max) of coding. The Mods in the discussion forms kept sandbagging, claiming the feature was extremely complex.
The initial step counter was a hit product with a specific niche. My impression is they've really struggled to keep up with growth and innovation in the field, and this IPO is very much an attempt at an exit of sorts.