While there is no exact "plot", the story is told as if it were an instruction manual. It details different inking pens, screentone, etc. Basically, a manga-style tutorial. It keeps to this "plot" very nicely, each lesson following the last, though they aren't necessarily related (pens have nothing to do with screentone, after all), but it's all related to the overall theme of tips and tutorials about creating manga. It wasn't hard to understand, even for me who has no history with creating manga and no intent to start (I just stumbled across this manga and thought it was very interesting).
The art doesn't particularly stick
out, but it details the pens and styling very well, and the characters expressions are fun as well. The style seemed fitting for this manga, and was consistent.
The characters did try to have a personality, but much of their dialogue was simply explaining the mangaka tutorial, so at times it fell flat. Their personalities were also very stereotypical and generic, but their conversations were enjoyable enough, and as I was mostly here for the mangaka tutorial anyway, I didn't mind. If you're looking for interesting, well-rounded characters though, this isn't for you.
Personally, I found this very enjoyable, as I like reading instructional things even if I don't plan on making use of the knowledge. If you enjoy browsing WikiHow or learning how to do things, this will be enjoyable. If you want to make manga, this will be useful. I don't think non-manga fans would ever enjoy this, and I don't think it's particularly re-readable for most people since once you've gleaned the knowledge from it, there's not much left.
Overall, it's a fairly memorable manga, and entertaining enough to flip through at least once. I'd recommend giving it a go if it seems like your kind of thing, but it's no huge loss if you don't.