Thanks for posting.
Having picked this up for myself recently, I will agree with you that the lens exceeded my expectations as far as sharpness goes. With the exception of around 150mm f6.3, I found the lens to be surprisingly sharp, more so than the 15-45 lens which is disappointingly average in this respect. That said, I found CA to be a bigger issue with this one than with most other lenses in my collection. Also, balance with the smaller M's like the M10 is slightly front-heavy. But for my uses, not really a deal-breaker. I like it overall. I do have the 55-200 as well but I'm going to keep it for now - besides the 50mm extra reach, it's also 2/3 stop faster in the equivalent focal range.
Also - if you use the built-in flash, keep in mind the long barrel will cast a shadow at the widest FLs (up to about 30mm).