Hey Gusto (love that screen name, by the way )... Yes it is very normal for an electric smoker's temp to fluctuate. Rather that producing a steady amount of heat, like gas or wood/charcoal, most electrics control temp by cycling the heat element from 100% on to completely off. The amount of fluctuation depends on how low the thermostat allows the temp to go before switching back on. Of course the quality (meaning expense) of the components will have a lot of influence over the overall temp range of the fluctuation. Also keep in mind that when you first turn on an electric it will warm the thermostat to the cut off point way before all the other parts of the box come up to temp. Once the temperature in the whole smoker equalizes the temp swings should settle down.
But this isn't a flaw in design, rather it's the nature of the beast. Some designs allow a big swing in temps, and some not so much. The thing to remember is that you need the average temp to be pretty close to your target temp.
I completely agree with the others who recommend a good quality thermometer. It's essential to have a reliable way to know the temp inside the smoker before you can expect to fine tune your smoker (and how you use it) to get consistent results.
Fortunately that's half the fun ... tinkering and experimenting with the equipment is a huge part of our hobby. If my smoker ever becomes perfect, I'll most likely start on a new one just for the challenge.
You're off to a good start with your MES... enjoy the ride and please keep us posted!