Should I update my MacBook Pro (2015) from High Sierra to Monterrey?

Only you can make that decision. Make sure you have enough free disk space. You could upgrade in steps to make it work better. Start with Mojave. How to get old versions of macOS - Apple Support Then if your computer is compatible.macOS Monterey is compatible with these computers - Apple Support Go ahead an download it. Be aware that any 32 bit programs will not work in Monterey.https://apps.apple.com/us/app/macos-monterey/id1576738294

helenafromdenton--

many Bluetooth fixes were included in 12.2.1 update. including battery problems caused as bluetooth side-effects.

if you have not already, try updating to that version and see if there is some improvement.

You MUST have a local, disk-based backup before you attempt major upgrades. MacOS does not allow you to go back unless you remove all traces of a newer macOS (by completely ERASEing the drive) and re-install the old version, then restore your files from backup.

Along that same line of thinking I suggest you move to 10.15 Catalina first, and only when you are certain it is working for you, move on to a later version. The reason I say this is that your first backup under MacOS Big Sur and Monterey and later will change the Time Machine drive format to APFS, which could make going back to an older version of MacOS much harder.

Be careful with the Big Sur update , make sure you have a backup of your status so far first. It loaded before I knew what to expect (it being my first backup on my MacBook Pro 16"). It slowed my Mac ,interfered with some connections, it took four Apple techies and each did a factory reset when they got stuck. and then along came Montetrey (I'm on 12.1 now), it cleaned up earlier problems and introduced a slew of features.

My thanks though to all those more experienced people than I that nursed me through the whole nightmare. I thought I'd broken my laptop.

Not if you use bluetooth earphones.

Since installing Monterrey my favorite Bluetooth earphones no longer connect. I've read a lot of people having the same issues. There seem to be a lot of steps that work for some, not for others. It's been a real problem for those of us who need to communicate with clients while working. Haven't been able to find any solution that works. Apple offers tips about disconnecting anything connected to your Macbook Pro, re-setting Bluetooth SMC LMNOP settings and disconnecting flange gonkulators or something. (Sarcasm.) Works for some. Not for others. My advice is to stay away from Monterrey if you rely on Bluetooth connections. It's a bummer. (Monterrey feels great beside that one major problem.)

I have that version and am still experiencing the same lack of connection. (Hopefully it works for her.)