It’s fair to say Amazon Halo got off to a rocky start. A fitness band that promised analysis rivals couldn’t deliver, the wrist-worn wearable may be simple but the machine learning running on Amazon’s servers is anything but – assuming you’re comfortable with all that personal data sharing. Now, Halo is adding Movement Health analysis as superslot another premium service.

Amazon Halo is $99.99, and comes with six months of Halo Membership included. Service is $3.99 per month after that. You’ll need to pay for most of the features: Halo tracks activity sessions, steps, heart rate, calorific burn, time awake and asleep, and sleep temperature without a subscription, but if you want tone analysis, body composition analysis, broader activity tracking, sleep stage tracking, and the new Movement Health analysis – in short, all the stuff that sets Halo aside from a cheaper tracker – that’ll cost you.

There’s no screen, no speaker, and no way to use Halo to flag notifications or calls from your phone. Whether that’s a plus or a minus comes down to personal taste. It does help with battery life, though, with 5+ days between charges my typical routine. Amazon’s default strap is a simple fabric one, available in three sizes; there are replacements in different colors, and in silicone rubber, that snap on instead.

It’s not the slimmest fitness tracker out there. It stands up a fair amount on my wrist – similar to an Apple Watch, but that has a display and a lot more going on inside – and the Velcro loop can be fiddly to close and get comfortable. Physical controls are minimal, with basically just one multifunction button. Everything else, including setup, is done through the app.

I focused my testing on Halo’s new Movement Health features, rather than some of the existing functionality. Halo can, somewhat controversially, be set to listen to your speech and analyze your tone of voice. That way, Amazon says, you can gain a better perspective on how you might sound to others.

Because I feel like the people I come into contact with each day have a right to know if there are always-listening microphones nearby, I opted to leave the tone analysis switched off. Similarly, I decided not to use Amazon’s equally-controversial body composition analysis, which involves uploading photos of yourself in tightly-fitted workout clothes or underwear to the company’s servers.

I don’t doubt that there are plenty of security systems in place around that, as Amazon says, or that the files are deleted straight away. Still, at a time when our data footprint – and particularly that footprint out on different companies’ servers around the world – is ever-increasing, I think taking a more circumspect approach to where we upload images of ourselves is prudent.

You’ll need to allow server-side analysis of Halo’s Movement Health too, of course, since Amazon records you in order to calculate how flexible you are. The official guidance is to wear “form-fitting clothing”: think along the lines of compression shorts, pants, or a form-fitting shirt, rather than baggy shorts or sweats. That’s because the analysis needs to see your individual movements, though it had no issues with my wearing a regular pair of exercise shorts and a standard t-shirt.