I have two of the plug in devices, an EM100 & a UPM model. They both work fine with similar features. As far as accuracy, well that depends I guess, on many factors, including the type of load connected. Here's a link to a forum with some comparisons & discussion.
http://www.dslreports.com/forum/r259...-Watt-VS-EM100
I suppose they're a good enough tool for checking individual appliances. From what I understand though, if you have a smart meter, once BC Hydro gets it all working the way it should, we should be able to see our real time consumption with an online app. on the BC Hydro site. I believe there will be or already are devices available that will work with your smart meter to monitor usage.