The difference between the WeMo Insight Switch and the standard Switch is that the Insight provides additional information such as power consumption and average usage. I also like the smaller form factor of the Insight Switch.
I am using the Insight Switch to control my air humidifier through timers on IFTTT. I have it set to turn on at night, and turn off in the morning. The Light Switch is controlling my kitchen light through IFTTT location triggers and my Amazon Echo. When I enter my apartment complex, IFTTT turns on my kitchen light so that by the time I get into my apartment everything is illuminated. And if I am sitting on the couch or on my desk, I can simply ask the Amazon Echo to turn off my kitchen light without standing up. So far the devices have worked flawlessly in this method!
Looking back at the reviews, it seems that the issue with WeMo is in the software. The WeMo app, at least on iOS where I tried it, is pretty bad. It would randomly crash and sometimes the switches will not immediately respond when pressing the power button on the app. However, it is pretty fast when I use the Amazon Echo to turn on my kitchen light. I took a video to show the response time and I find it fast enough for my needs.
Overall, I believe if you are not solely relying on the WeMo app on your phone to switch on/off your appliances, the WeMo switches are great. It's an easy start for those looking to try home automation without requiring a control hub and deciding on one ecosystem (WeMo works with just about every system, and HomeKit support is coming soon). Maybe the earlier versions of the WeMo products suffered from issues which have been fixed in recent firmware updates, but I am happy to say I am very pleased with them and plan on buying more when needed.