Earlier reviews and comparisons on FPN
The softness control
The unique selling point of this pen is, of course, its "nib softness control" which works by controlling the movement of the tines and thereby the stiffness of the nib. As has been emphasized by many others, the Justus 95 is not a real flex- or semi-flex pen. Instead, for normal everyday writing, it is a pen that offers both a bouncy and a stiffer writing experience. With M nib, the soft, bouncy setting writes a somewhat wider line (verging on Western M) whereas the stiff, rigid setting writes a narrower line (verging on Western F). My personal feeling is that this difference in line width is caused by controlling the flow of the pen, not by the tines moving apart. Neither setting offers line variation when writing in a relaxed way, i.e. with minimal pressure. 'True' line width variation due to the tines moving apart only happens when you press down pretty hard; even then, the pen is no match for a true flex- or semi-flex pen.
Still, the softness control is quite intriguing and my hand tells me that it really works. The soft setting is definitely bouncy and feathery. The hard setting is much more rigid, but still noticeably softer than pens with 'nails', such as Sailor (I'm not putting down 'nails', I adore Sailor!). Also in the hard setting, some line variation is possible if you press down.
Here are some writing samples, but note that the effect of the softness control is very hard to photograph. My eyes see it clearly on the page, but not so much on a photo of the page.
^---The H(ard) setting of the Justus is at the top, the S(oft) setting is 3rd from below. The difference in line width is significant!
Seen through a hand lens, the nib appears to have a perfectly rounded tip which promises a smooth writing sensation. Guess what? It's got lots of feedback. Not tooth, not scratch, but feedback. The nature of this feedback is much less subtle than the feedback of a good Sailor nib. Out of the box, it feels quite rough and unsophisticated in comparison. A quick examination learned that the larger the writing angle, the smoother the pen writes. The feedback is generated by the lower end of the tip. Easily solved, but might be a put-off for some.
The fact that the nib is not butter-on-hot-glass-smooth is a plus for me, because it allows me excellent control over my writing (which can be too fast, too angular and too jagged).
Out of the box, wetness is sufficient but the flow is a little bit irregular, i.e. some strokes are thinnish and dry-ish and others can be wet to the threshold of feathering. I've had MB Lavender Purple and Iroshizuku Shin-kai in the pen, with similar results. After about an hour of writing, the flow evened out. I have a feeling that it will become just right within a week or so.
Another intriguing feature: a converter with an intricate push-mechanism that I had not yet seen before. The physics of it are not yet clear to me, but it sure works well. Addictive, too - it feels nice to press and release that button and to see the ink flow in. Ink volume is sufficient.
Why did I buy?
The main reason for buying this pen is because it adds something unique to my little collection, its distinguishing features being the softness control and the converter mechanism. Both strike me as ingenious, well-engineered, functional and fun. The rest of the pen is of high quality and should last a lifetime.
The price is steep. Perhaps too steep. The same price buys a wonderful Sailor 1911 'Simply Black', which is a truly superb writer (yes, I tried) and for just a little bit more one can buy a Pelikan M400. If it's worth the price is something that you can only decide for yourself.
+ quality of build and materials
+ weight, dimensions, comfort
+ attention to detail
+ 'softness control' really works - but it changes the feel of the pen from rigid to soft - it's not flex!
+ 'softness control' also seems to influence wetness, which changes line width from narrow (western F) to wide (western M)
+ ingenious converter mechanism
+ degree of control over handwriting
/ feedbacky nib, especially with small writing angle (60 degrees or less)
/ line variation due to tines moving apart only possible with significant pressure and perhaps not without risk
/ irregular flow out of the box, could be a break-in period thing