Hi Amit,
Ideally we should push the official integration from TP-Link to support the Energy Monitoring (EM) function, as the box of the KP115 has the ‘works with Smartthings’ logo and there does not seem to be a disclaimer visible on the packaging itself about the lack of EM functionality when working with Smartthings.
I am using the ‘new’ Smartthings app on Android (but holding off on upgrading beyond the current 1.7.57.23). The SmartApp works very well, but I had to do some tweaks to get it to work (see my other post TP-LINK HS110 - Power usage for washing machine - #4 by ernie) and the user interface of the SmartApp does not look ‘right’, but it functions once figuring out where to press at each step.
Also note that I have both the SmartApp and the official TP-Link|Kasa Smart linked service connected, so I have a duplicate occurrence of the devices, but have parked the ones through the linked service in another room that is not on the Smartthings app main screen. It gives me a secondary way to get at least to the on/off switching part.
Not sure what the upcoming changes in the Smartthings platform are going to mean for my setup, so am holding off on investing additional time to investigate what I could do in terms of modifying the existing integration, or if a new device handler can be written that does not require the SmartApp.
Hope this helps a bit =)