Pro
The mushroom chart as can be seen in the image above on the left solves a problem that the lollipop chart has as seen on the right of the same image. The problem is that "the centre of the circle at the end of the lollipop marks the value, but the location of the centre is difficult to judge, making it imprecise compared to the straight edge of a bar, and half of the circle extends beyond the value that it represents, making it inaccurate." As highlighted in the image, the "stalks" (or the bars) can be seen that the mushroom chart can be placed at the centre of the chart. Although this is possible too for the lollipop chart, the chart becomes less intuitive considering that readers will normally take the centre of the circle as a point.
Con
The issue however is that the caps of the mushroom may be unable to cover the edges of the "stalks" fully, by jagging from the cap. This may be solved by thinning the "stalks". Nonetheless, is there then a purpose for the bars if they are so thin that the focus becomes the mushroom cap? Perhaps, we may as well stick to bar charts as the way to go if the circles or semicircles above the bars do not serve any purpose. The bars can be similarly labelled with colours unless one labels the circles or semicircles in different colours from the bars. Or if the sizes of the circles and semicircles matter like the thickness of the bars.
All in all, the idea of how the lollipop chart may mislead viewers and how the mushroom chart may help can be thought-provoking to a data viz enthusiast, but the viewers themselves may not concern themselves with such topics as long as the number labels are provided and the viz do not look bad.