It's bafflingly terrible. It wastes far too much screen space. The edges of the window have no visual distinction against whatever other similarly colored windows are underneath. The dialog can't always be moved around, and when it can it is sluggish. The sprawling new layout requires too much unnecessary scrolling. Elements that appear to be clickable, such as alternate locators, are not clickable, nor even copyable by right-click or manual click-and-drag. I went through a couple rounds of toggling the "NEW UI" button on and off, and now the Object Spy seems hopelessly bricked, even after a TestComplete restart. At the moment I can't even drag the crosshairs, and the dialog won't close when I click the "X" icon. Next stop: Task Manager, then Reboot. Others on my team have also reported that whether the Object Spy works for them on even a basic level is sporadic.
This is a confidence killer for 15.84. I think I'm going to have to roll the machines I upgraded back to a last known good; thanks for that. /s
Please don't release any untested messes like this in the future. And please abandon all plans to implement such a space-wasting UI change. It's already hard enough to fit everything I need on my monitors without TestComplete deciding it wants to dial whitespace up to 500%. Usability trumps aesthetics, if you want to keep selling solutions to people who have work to do.