It does more than give the power estimate.
When it's on, if you move the aimer forward and back the meter scales automatically change. I'm guessing that many members will find this annoying, especially those who prefer to use the short end of larger scales.
If you manually change to a scale that the game judges to be too short to possibly get to your aim point, the up arrow flashes several times. If you change to a higher scale than needed, nothing flashes.
It seems fairly accurate on medium-length putts. I tried slow and tourney greens and various routine elevation changes and it adjusted properly. The right answer was always in the green zone.
It completely failed on StA 11 from 67 feet right of the hole (back pin) on tourney 12 greens, coming up well short on a putt with 3 feet of uphill even when fired fom the high end of the range. Same thing on StA 12 (back pin) putting from the bottom shelf. A putt from the high edge of the green zone barley made it up the rise.
I think they're using the feature to test caddy improvements, so I recommend that everyone have a look.