Yes, I do have one. Two.
I slipped sideways from a *real* Pen FT (film) into getting a Pen E-P2 when they first came out. A tiny adaptor and i was using the older Olympus half-frame lenses on a modern digital camera. But I never really liked the ergonomics of the E-P2, so when I was able to afford it, I sprang for an OM-D E-M1. By then I'd bought a few good lenses, and the M4/3 lenses I have are the very best lenses I've ever owned. The 40mm and 75mm lenses in particular are unimproveable.
I look at pictures that others have made on full-frame cameras and know that I can never reach that level of detail with my M4/3. But it isn't far off, and I gain a lot just by size & portability. I'm not at all sorry I bought into it!
I'm still shooting film every day but for some things (like Alex said, birds in particular), the OM-D is what I use.