I recently got a Sony VCL-M3358 (which basically appears to be a +3 dioptre lens but implemented using 2 elements in one group). We have a smallish araneus spider that has happened to build a web before a crack in the living room window pane.
This is basically what the camera (DSC-H1) says on its own from the vantage point I've taken the subsequent photograph from, zoomed in as much as the camera will allow without losing focus:

Without close-up lens
This already uses some not-so-accurate white balance setting since the (reflected) window stoles are actually white. Now with the macro lens attached, I can zoom in a whole lot more since ∞ in the camera lens' perspective maps to 33cm in reality. So (same setting, different scene) I get

Spider with VCL-M3358 lens
The crack in the glass has left the depth of field significantly and makes for some perspective effect. The windows stoles have essentially dissolved, possibly also because of using a flash, reducing their contribution to the overall lighting. The narrow depth of field warrants a smallish aperture.
In postprocessing I realized that it might be fun to turn the crack into some kind of horizon. The framing/orientation does not leave a whole lot of leeway, but one can make do with rotation and cropping just as much as necessary.

Rotated and cropped
I call this "Don't pay the ferryman" since it may be considered sort-of like a water surface.
In summary, the main challenge with the close-up lens so far has been focus: getting the most out of a rather narrow depth of field.
But then that's probably not exactly news to most of you...