As a software engineer and home automation enthusiast, it's rare that I find an electronic gadget that does exactly what I want. When I do, I buy a few, even having no immediate plans for them, because I never know when they'll be discontinued and replaced by a newer version that just doesn't work as well. This Kasa smart outlet from TP-Link is one such diamond in the rough. After putting one into operation, I have purchased four more just to have on hand.
The deciding factor? Total local control. I hate IoT gadgets that depend on "The Cloud" for part or all of their functionality, as their usefulness diminishes or disappears when their manufacturers eventually go under, get acquired, or simply decide they no longer want to support their older product lines. These Kasa smart outlets work without needing to "phone home." In fact, I blocked my unit's MAC address in my router's firewall so that it *can't* reach the Internet, as I have security concerns about IoT gadgets, and it's still completely usable via a local protocol over my LAN. Of course, cloud-based integrations won't work in this configuration, but that doesn't bother me.
I especially appreciate that the energy monitor features of the KP115 are accessible over the local protocol, too. The only feature that might not work without giving the unit Internet access is the scheduling feature, as the unit can't set its internal clock without Internet access. (I haven't investigated whether there's a local command to set the clock.) [UPDATE 2021-09-07: The device does have a command that allows setting its internal clock. Once the clock is set, the device starts saving per-day and per-month energy usage statistics, which are retrievable via the local protocol.] But I wouldn't do scheduling on the device itself anyway; I'd do it in home automation software. I only need the device to switch on and off when commanded and to do so reliably, and to that end the KP115 works a treat, especially for the price. You can't buy a Kill-A-Watt meter for this price, and those don't have Wi-Fi or switching capability. Moreover, the readings of voltage, current, power, and energy have greater precision than on the Kill-A-Watt. Only disadvantage, if you could call it that, is that the Kasa doesn't have a display; you have to read the meters via Wi-Fi. No big deal for me. The energy consumption meter *does* survive loss of power. There is a local command to reset it to zero.
Aside from the local control aspect, the physical unit is attractive and sleek. It does not block the other receptacle in a duplex outlet. The blue power indicator LED, which lights when the switch is closed, can be disabled if you find it distracting. The mechanical switch does make a click when toggled, but it's not too loud. The switch remains in its current state when the unit loses power and will remain in that state when power is again applied, and no click is heard at either point. I take this to mean that the switch is not a simple relay and is in fact a bi-stable mechanism, probably one that consumes essentially no power except when transitioning between states. The contacts are rated for 15A.
So, in summary, the Kasa KP115 is an EXCELLENT smart outlet if you, like me, are wary of giving closed-source (unauditable) devices access to the Internet in your home or simply don't want the devices you buy today to become landfill when the companies that made them give up on supporting them. As long as 2.4GHz 802.11n continues to be implemented by home Wi-Fi networks, these KP115 smart outlets should continue to do their job admirably.