I debated fitness trackers for awhile before replacing my old charge 2 with the charge 4. I've not been disappointed!
Pros: Accurate heart rate and sleep tracking (including oxygen level fluctuations), and I really like the Active Zone minutes feature, which tracks your cardio activity toward a goal each week. Plus, they have a good variety of programmed exercise options - I've tried boot camp, weights, walk, run, swimming, and kayaking ("outdoor exercise"), and they all tracked well. It syncs easily with your phone for notifications (or that can be turned off if you want to disconnect). I like that it has a button feature for control. Also, I have a small wrist, and I don't like anything bulky, so I appreciate the size.
Cons: It's hard to wake up the screen just by raising your arm (can take a really big arm swing and it doesn't always catch it without using the button), and if you're outside in full sunlight, the display is hard to see. I had also read enough reviews about the GPS draining that I decided to turn that feature off for walks or runs, though to be honest, that hasn't really bothered me, since it's still tracks distance and other stats like that without GPS. If I go for a longer hike, I'll just plan to turn it back on.
Overall, the charge 4 has the features I wanted without the ones I don't, and its smaller size means I can forget it's there when I'm not working out.

So, first of all this is my very first tracker. I love the design and the relative ease of use. Also not having to have my phone on my is great!

So here are some pros and cons.

Pros: comfortable, accurate gps, great battery life even with my constant Bluetooth connection. I don't have the issues with buzzing that other people have! Maybe because of how I wear it idk.

Cons: sleep tracking doesn't work consistently, I've only gotten maybe a week worth of data after months of owning it.

The wrist band snapped within a few months. I do not wear this tightly. My wrist is very small. I do not shower with it. Not sure why this happened, but they only include one extra strap in the box, and it's not the side that snapped. I ended up buying new straps off Amazon.

Sometimes the device malfunctions and there's no way to power it off when the screen doesn't work. I just waited until the battery died and it's like it never happened.

I have to tell you this, the app takes getting used to. But now that I am wearing it on my wrist, there are no more excuses for not going 10,000 steps each day! Furthermore if you are an AARP Medicare member, you can hoist your fitbit to download your activity into your uhc.com account and get rewarded. Most senior members of AARP Medicare Advantage Plus need only 7500 or 45 minutes of activity on 10 days each month to be rewarded with 10 dollars through a VISA sponsored program.
Use it or lose it!

I was hoping to have this watch for a few years, but after about a year of owning my Fitbit (with normal use), the part of the watch where the straps connect broke. It broke in such a way that it cannot be fixed - this is a problem that other people have also reported, where the screws that hold the connecting mechanism to the Fitbit shear off for no apparent reason. In fact, I had never even changed/disconnected the watch straps before the watch strap just fell off. I reached out to the Fitbit customer support, and they only offered me a coupon for a next Fitbit purchase, which is silly because there is no way I would purchase another Fitbit after this issue. If you're wanting to buy a new watch every year, this one is pretty good for a smart watch. If you want something with longevity and a company with solid customer support, look elsewhere.

I missed having my charge 4 after losing my first one. Nice to have this new one.