After using it for some time now, please add me to the list of people that "don't like" (which is an understatement) the new interface. I honestly don't understand why you fixed something that wasn't broken in the first place (other than some web programmer wanting to show of his "skillz").
The new UI in my opinion is very counter-intuitive. Often you click something and get no/little feedback at all that something has actually happened. Requesting location for instance. You click the "Locate" button, and you are presented with a map. None of the buttons on the map have a tooltip, so the only way to find out what they do is to actually click on them. It also took me a while to figure out you actually need to click the "Request Location" button. After you do, a message appears that it is trying to contact the device. That message changes in "Command sent succesfully" (or something similar). After a while this message disappears and nowhere on the map do you find any indication if it has successfully aquired the device's location. It still shows the last known location from your previous locate command. Nothing changes on the map. As it turns out, the only way to find out if the command has been successfull, is to close the map and reopen it. Incredibly counter-intuitive.
The map itself is a mess. There's no easy way to tell by just looking at it what the last acquired position is.
And sometimes you close the map, and reopen it a minute later and you are presented with an empty page with the text "No positions have been uploaded. Please use the Locate command to request device position." If I click "Request Location", it's unable to contact my device. Looking closely, I noticed it has switched devices, even though I never clicked on another device in the list on the left.
And last but not least, the site does not work (properly) on mobile devices. It has been designed for desktops so trying to view it on a mobile device gives terrible results.
I'm not one of those "because it's new I hate it" people. I gave it a chance and tried to use it. But the new UI is so annoying to use, I'm seriously considering switching to another app. I know it's free and shouldn't really complain, but I honestly was about to buy the pro version but the new UI is a deal-killer for me.
I know you will not kill the new UI and bring back the old version, but please consider giving us an option to use the old version again. So that people who like the new interface can use the new, and people like us can use the old.