I average 10+ hours a day at my desk. When my old Logitech stopped working, I rushed out to by a replacement. I planned on getting the exact same keyboard (K750), but I saw the K780 and figured I'd give it a try. My first thought was that it looked strange with (unnecessarily) round keys, and I wasn't sure I would like it. That said, the ability to connect to my computer, ipad, and iphone at the same time, sounded very appealing - and it was on sale for $59.99. Well, my skepticism lasted all of about 10 minutes. I love this keyboard. In fact, I've never been so geeked up about a keyboard. I now have one in my office and my study at home. Typing is surprisingly enjoyable. No issues with the round keys. It's not as clickly as I typically prefer, but the overall experience is very enjoyable. If you don't usually go for the membrane style keyboard, I suggest trying this one anyway. I can't explain it, but Logitech has something here.
Now, onto the important stuff. If you regularly use multiple devices at a desk, this keyboard will seriously increase your efficiency. It is hard to overstate how much I appreciate the ease with which I am able to operate my PC, iPhone, and iPad Pro throughout my day. Streaming videos, responding to texts, surfing "non-work" websites, and getting all of my sanctioned work done on the PC at the same time with the same keyboard. Switching devices is fast and easy - just one click. Click again, and you're back. No need to stop and pick up the phone every time you get a message. In the two weeks I've been using the K780 I've actually learned many keyboard shortcuts for ios, which saves me even more time and touches on my ios devices. The keyboard is heavy - but you will appreciate that when you've got your tablet and phone sitting in the channel because the keyboard is stable and never feels like it's going to fall over. That said, if you have a charger/stand/docking station, there is no need to use the built-in channel because the devices are connected with bluetooth. So, depending on what I'm doing, I may have my phone or tablet resting on a separate stand or charger, but the keyboard functions just as well.
Bottom line. If you're stuck at a desk for several hours a day, and you enjoy using multiple devices - you will, at a minimum, appreciate this keyboard. If you're like me, you're going to wonder how you ever got along without it.