Regarding the product itself, it is very good, it is not plastic but metal which it is made, the lenses do well their work, I rode on my 18-55 (which a 52mm thread) and he walks delighted, the macro is not practical with the 18-55 objective but it works very well, test it on my ring quality is there, concerning the distortion that can be, do not forget that this goal will not correct the distortion based on your purpose;) good but a passage in Ligthroom and / or photoshop (or gimp for sure) and voila.
The wide angle is bluffing, I really did not expect this, I have an APS-C sensor and yet the scene is vast and you really feel like a 12mm lens in hands. so I do not imagine those who have a full-size!
If I met him that it is only 4/5 because it lacks a manual that could be used in particular for the non-connoisseur macro.
Ps: the goal of a thread 62 mm (for those who want to buy a UV filter / neutral gray)