I upgraded from an Edge 530 for the bigger screen, as I am getting older and having a harder time seeing things. And the screen itself is great.
The bell is a nice feature as well.
That being said, this product is really buggy. It has been out for almost a year and it has many issues.
1. It randomly reboots in the middle of rides (it doesn't lose the GPS up until then, and after reboot you can hit start to continue recording. But if you are in the middle of a Strava segment, it gets dropped from your results, which is annoying).
2. I often (80% of the time?) need to reboot this before going for a ride as the buttons stop working. The touch screen and actions mapped to my di2 buttons work, but since I didn't map the start/stop to a non-physical button, I cannot start the ride. Long pressing the power button works to reboot and restores functionality.
For a computer this price that has has a bunch of time to push updates, I think this is pretty bad behavior.
I bought this to replace an Edge 830, which I was very disappointed with, as I have been with all my Garmin units, starting way back with my 500. The problem is Garmin doesn't support older units; once a newer version comes out, forget getting bugs fixed on the old one. And maybe there is a reason for that (older hardware can't handle it), but of course they sold the old ones with the claim that all the prior problems were fixed.
Example: phone connectivity was supposed to be fixed on the 830 (from the 810), but it was as random as before, never stayed connected/paired whatever. And the claim for the new 540 is the same; so far, it actually does stay paired, so maybe it is fixed? But the point is, it may be fixed now on the 540, but they are never going to fix the 830 or 810. And that is sad for the cost.
The 540 is clearly faster; that was a big problem with the old units, as they just seemed to crawl in map updates, even to the point of having the graphic hang up at critical points. And don't confuse it by route following or some other computation; it will screw it up. But the 540 seems fast enough that I haven't noticed a problem.
Of course, that leads to my major gripe, an unannounced change from the 830: they removed the perspective map view, which is essential for seeing both near and far. You know, like every car navigation system (made by Garmin) can do. I am really disappointed here.
I deliberately didn't get the touch-screen of the 840 because I had it on the 830 and it was terrible. Not worth it. I still touch things, only to realize the buttons have to be used, but overall I prefer buttons. If they could make a touch screen work in the rain, winter, etc, maybe I will change my mind, but I won't believe it if they claim so. They claimed all that before, and they lied.
Yes the newer climb pro and other new features are incrementally better. At least when a turn comes up on a climb now, I get the intersection image so I can make the correct turn. That was a big flaw in the old one. But most of the other new stuff is less impressive, like training plans and "connected" features.
I know this sounds a little negative, but I am a grumpy old man. This ranks as a positive review in my book.
I got these for road cycling, but I ended up using them mostly for running, because that's where they shine (and as the name implies, that's mostly what they are for). I pair them to my Garmin while running and have zero complaints. They are excellent. I do also using them riding, but obviously they are open ear headphones and if you have any significant wind noise you will have to crank the volume to get decent audio, which defeats the purpose because you can't hear what's around you. I can't wait to try these while mountain biking when it gets cooler, because I bet they will be outstanding at those slower speeds. They are also great for longer road climbs and you can just deal with the wind noise on the way down.
I'm not familiar with other, similar units ' although there are a few. I purchased this because of my experience with other Garmin products' and it was on sale! So far, I've not been disappointed as it does everything I'd hoped for. One thing I've noticed is that if using the screen on your phone, the traffic icons are spot on' as opposed to shutting the screen off and relying on the audio alert only: in this case, there could be two cars when you're expecting only one. That said, I still use my mirror to be sure. I also like the fact that you're given plenty of time before traffic comes near you' just in case you need to do some emergency maneuvering. If you're curious about radars, definitely check this one out!
BTW: I use an IPhone 12 with the Garmin Varia app. I understand it will also work with Ride with GPS, but I haven't tried that as yet.