These scales are much better than my old mechanical ones. They are smaller, and have a stand that enables them to be stored upright (e.g. in a corner or on a shelf) without them falling over. To use, you get on, wait for the beep that tells you you've been weighed and then read the result. Easier than bending down to read a dial (the shift in balance made the dial on my mechanical scales jiggle about, and the dial was getting harder to read as I got older).
The scales weigh to an accuracy of 0.1 kilos (they also weigh in stones and pounds, but I like kilos). At that level of accuracy you will see the changes in your weight due to how recently you ate/drank/went to the loo, as well as any longer-term changes you are working on. That's NOT a problem with the scales: if you just drank a pint of water, you temporarily weigh 0.5kg/1 lb more, because that is what the water weighs. So the scales are being accurate in telling you this. The advice that I've seen is that you should weigh yourself at the same time every day. That way, you can see what is small fluctuations and what is a trend.