I have been using modern fountain pens for about a year, so I am not an expert. But, I wanted to review this Slate Gray Medium Nib Prera.
Color: I really like the color. The color is classy and professional enough for a mature senior engineer to take to work at a conservative company.
Writing result: This is my second Prera. The first one is a brown with a fine nib. This time I wanted a pen with a bit wider line on the paper, so I bought this medium nib version. I am using this pen with Pilot/Namiki blue/black cartridges. This combination results in a very smooth writing pen. No problems. Since I have been using my fine-nibbed Prera with several brands of bottled ink with no problems but one, (a fast drying ink that caused slow starts when left uncapped), I expect very few problems with various bottled inks.
Cosmetics and durability: I have not experienced the scratching due to posting the cap as others have. My original brown one and this new one still looks nice and new. I have not had any problems with the nib and feed falling out. If I change colors, I have to pull the nib/feed out with "intent". After cleaning, it pushes back in place with friction and stays put.
Weight: These are lightweight pens, much lighter than the Metropolitan. I personally like that because it doesn't pull down on my dress shirt pocket. Speaking of shirt pockets, I like the way the clip is designed so that the top of the cap almost sits even with the edge of the shirt pocket. All you see is a neat-looking clip and a little bit of the end of the cap.
Length: The pen is a bit shorter overall, so the pen will ride straight in most any shirt pocket, yet is long enough to take a quick note without posting the cap. Longer writing sessions will be more comfortable with the cap posted.
Conclusion: My Preras are my go-to pen these days. I would recommend them to anybody looking for a pen of this configuration and price point.
So there you have it. I hope this review helps.

I'm so sad that this pen didn't work out. It is beautiful and wrote beautifully but I've had two pens within the past year and both failed radically. My first pen cracked after only minimal and light use. Jetpens replaced this pen and after a couple of months of light use of the replacement pen the nib and feed fell out of the pen. It is so frustrating that these issues occurred and that both problems created complete failures of the pens - not just cosmetic or reparable problems. It is truly disappointing. :(

It is a great pen. I upgraded from an old Parker 45, and the medium nib is very smooth.

The only gripe I have is that the color is quite a bit lighter than what is shown. The photo makes it seem as if it's a dark slate gray, when it is closer to just slate gray. Photos elsewhere on the web show a better representation of the color.

I am still very happy with the pen, it is a unique color without being flashy.

Love this. I have stepped away from the pilot metropolitan because I didn't like how it dug into my hand, and the metal felt a bit too heavy for me. I missed the smoothness of a pilot m nib though. This pen is perfect. It is not too heavy, there isn't anything that digs into my hand and when it is posted it is the perfect height for me. Just a note - this pen is on the shorter side even when posted, but with my small hands it is fine! I love the slate grey, but hope to get it in more colors in the future.

I did not expect to love this pen as much as I do. It has gone straight to my every day carry kit along with my Kaweco Sport BB nib. Fountain pens are my primary drawing tools as well as writing instruments. I want a fuss-free pen that feels sturdy and writes effortlessly. The Prera meets all my expectations. It is a short pen, but not skinny and it is very comfortable to use when posted.