Let's start with the negatives of the sprayer. First, you can't see how much material is left inside; second, the straps are short and cheap, which makes it difficult for you (add some pads or a towel), third, its shape is like a bubble, which makes it hard to carry on your back. Fourth, all the nozzles included are useless and you need a metal one to do your job properly.
Despite the negatives, it also has positives because there are even worse ones, e.g., compared to a Geotec battery sprayer I also had, but this one is much better. First, the fact that the battery is lithium makes it much lighter and more manageable, and its duration is by far much better. Of course, if the battery breaks, it's better to throw it away; it's not worth buying a new one. I wonder why they don't use the clip-on batteries like those on tools, which are even lighter.
Second, its pressure is very satisfactory, even for a professional farmer. For a friend who had trouble figuring out how the potentiometer works, let me say that the sprayer has on and off. When it's on, the sprayer works at maximum pressure. When it's off, you then turn on the potentiometer and adjust the pressure.
Generally, if you find it for 50 euros, it would be a very good purchase.