I bought a Garmin S10 golf watch/band a few years ago. It works well most of the time, but GPS is finicky and heavy tree cover can interfere. Also, it requires that you remember to tell it when you complete the hole. Otherwise it thinks you are still on #3 when you are taking your second shot on #4. Pros: Fast, works everywhere on the course. Cons: gives you mid green distance (mostly), can be off, may lose track of where you are.
Got a Nikon rangefinder (20 year work anniversary gift) in July. Much slower to use than the GPS watch. You need to pull it out, line up the flag, hope the flag isn't on the green (group in front of you) or not visible (hills, dogleg). Sometimes it latches on to something other than the flag. Pros: accurate when clear line of sight to flag, nothing on wrist, simple. Cons: requires line of sight, can miss the flag, mine is small and so is shaky.