I have one of these and despite the issues some people here have had i have had a wonderful experience with mine.
I purchased mine used from someone here on the fpn. later on I noticed it had a tiny crack in the nib housing which caused a tiny leak. I sent it to Yafa who happily replaced it for me free of charge.
it originally came to me with a M nib which wrote wonderfully. once i sent it back to yafa for the replacement i asked for a .9 italic since they decided to replace the pen.
The nib screws out of the pen and the nib pulls out from the nib section. so it is possible to make your own adjustments. With the original M nib it wrote perfectly but the newer .9 italic was a very dry nib. After some adjustments by me (took less then 10 minutes to get it perfect) it was a smooth wet writer. Just like i like my pens.
needless to say it has become a daily carry pen which i have used since i purchased it here on the FPN.