Unless you are an excessive user of polarizing filters, it's a great lens.
In my book, filter use and its relatively high price are the two only weaknesses of the 40mm.
Aside from that, it is very much as typical Zuiko: Small, light, sharp.
The 40mm view angle is very versatile, and being able to focus much closer than the 35mm and 50mm Zuikos (not considering the 50 macros), achieves a relatively large maximum magnification.
All in all, it is the best one-for-all Zuiko to mount on your OM camera.