I upgraded to sense 2 from a 7 year old Charge 2 and I have to say I love it. It does everything I personally need from a fitness tracker. Battery life lasts 6 days most of the time but can be less if using your gps. Some of the advanced features with the free trial of Fitbit premium drain the battery. I did have one glitch where the battery drained over night but I removed sp02 tracking and daily readiness, and it then went back to normal at 6 days. The ECG function is good and gps worked well when I tested it on a 9 mile walk. You have to physically turn on gps in the exercise settings which is fine, otherwise it drains the battery a bit. Yes it takes a minute or so to kick in and you can tell once it’s on as the little gps arrow is red whilst kicking in and white once on. Steps are accurate, as are the floor counting. I can take calls on my watch (once I linked it to sense 2 calls on Bluetooth) which is great as you never miss a call if you’ve left your phone in another room etc Obviously you can’t make calls or texts from it as it’s not linked to a phone contract, but I find it useful to be able to take the calls and the sound on it was fine. I personally love the Fitbit app, and the way the calorie tracking and targets work. It is glitchy occasionally but what app isn’t? That really doesn’t faze me as the data is on your watch and always syncs again once the app is fixed as long as you don’t reboot your watch during that time. In 7 years of using Fitbit I have only ever had a handful of issues with the app. The ability to change clock faces is good but it would be nice if there were more that showed battery life as a lot of them don’t. Overall, a good tracker but if you are a massive fitness fanatic who wants a lot more of the advance features some have like fall detection, quicker gps, ability to make calls etc then you may want to opt for another brand of Watch. For me though, the sense 2 is perfect for what I need.

The Sense 2 stands out as a health-first smartwatch. It's clearly built with wellness in mind rather than trying to mimic a phone on your wrist. From tracking heart rate and sleep to managing stress, it offers tools that feel useful rather than gimmicky.
What I liked:
Detailed Health Metrics: Heart rate, ECG, skin temperature, and stress detection are built in. The stress tracking, in particular, is easy to overlook but quietly helpful when you're trying to identify patterns in your day.
Sleep Tracking: Sleep Score and sleep stage breakdowns give a clear picture of your rest. If you're trying to improve sleep habits, this adds useful context.
Excellent Battery Life: It easily runs nearly a week on one charge with regular use. That's with 24/7 tracking and the always-on display disabled.
Comfortable and Discreet: It's lightweight, slim, and doesn't scream "smartwatch," which is a plus. Comfortable enough to forget you're wearing it.
What could be better:
Smartwatch Features Are Limited: You won't find app support, music controls, or anything close to what Apple or Samsung offers in that department. Notifications are basic.
Premium Paywall: Some of the insights-especially more detailed analytics and guided programs-are locked behind Fitbit Premium. That means another subscription if you want the full package.
Final Thoughts:
Fitbit Sense 2 isn't trying to be everything-it's focused on wellness, and it does that well. If health tracking is your main priority, this is a strong choice. Just be ready to pay for Fitbit Premium if you want the extra data.

This was bought to replace a Fitbit Sense 1 which had broken. The Sense 1 was always a little finicky. Sometimes it wouldn't charge, sometimes it'd only charge halfway. The sense 1's footstep detector was wildly inaccurate. About the only thing it did well was the heartbeat thing, which was quite accurate.
The Sense 2 fixes a lot of these issues, and makes for a faster, smoother experience. The Sense 1 would lag occasionally when swiping, but the Sense 2 doesn't. It's a better watch all round, I think.
We both, originally, paid for the subscription, but it just didn't seem to give us anything worthwhile. Apps like Zombies Run! give you fun, cool things to do to get fit. Other apps give you recipes, or fitness ideas, or reminders etc… I just feel that the fitbit ecosystem has stagnated a little and they're just selling smartwatches/fitness trackers without evolving the experience.
So, there's one thing that's the same with both, and it's still a disappointment, the app:
The thing that annoyed me about the Sense 1 was that it constantly had a "disconnected from phone" icon on the screen, despite the phone sitting RIGHT THERE. What's the point of having a smart watch that can control the phone, if it only works if the app is loaded and showing on the phone's screen?
I can count on one finger the number of times that I've had the Fitbit app loaded, and someone's tried to call me, and I've been able to answer it using the smart watch.
The sense 2 does the same. Despite having the App on the phone, it still doesn't detect the phone unless the app is loaded. And sometimes you'll load the app, and it'll take ages for it sync with the watch, despite the watch being in the active bluetooth devices list.
I know Bluetooth is a bit flakey, and not all devices are equal when it comes to supporting different profiles, but I would have thought the one thing the watch was supposed to do (exchange information with the app) would have been sorted.
The watch was for my wife, and she's had no problems with it so far. She likes the features, but doesn't use much of the additional functionality. She occasionally loads the fitbit app to sync the data and see how she's been doing. but, if I'm honest, I think the App needs a major overhaul. She shouldn't have to take the watch off, and lie it next to the phone for ten minutes to sync for her to know how many steps she's taken, or for the most useful information to be buried under a dropdown, which is in a tab, under a graph, which is about four scrolls down. The app has most of what you need, but it could do with a little of a redesign I think… Perhaps find a way to let people configure their dashboard, both in the app, and on the notifications, or widgets on the home screen.