About a year ago, a pen friend overseas asked if I could help him to find a replacement Lamy Nexx, with a yellow cap. I knew very little about the Nexx but read that the yellow (“Citron”) was an edition from 2015.
Our local WH Smiths at London’s Brent Cross shopping centre sells the Lamy Nexx but I have seen only the lime green cap version there, in contrast to their wide selection of Safari and Al-Stars. However, as luck would have it, finding a yellow one online was a piece of cake as they were available from the Hamilton Pen Company. I took the opportunity of ordering two, to try one for myself.

I had seen the Nexx for sale many times, hanging on blister packs beside the Lamy Safari and Al-Star range, but had never bought one, dismissing them as a bit childish. Also, although I have bought plenty of Safaris and Al-Stars over the years, I did so despite the faceted grip, not because of it. As a lefty over-writer, who rotates his fountain pen nibs inwards a few degrees, the facets do not align with my fingers and consequently I am left with thumb and forefinger resting on uncomfortable ridges rather than the intended facets. I can hold them if using my under-writer style but this is not so natural for me and therefore limits my use of the pens.
There is a big difference with the Nexx: the grip area is of a black rubber and the edges of the facets are not so pronounced and the edges are not at all sharp.
Design and construction.
The Nexx is a robust, workhorse of a pen, if ever there was one. The barrel is made of a aluminium with a silvery, satin finish and blends from being round, next to the grip, to being triangular (but rounded off) at the back end. The grip section is of black rubber and of generous girth. The cap is of a tough plastic with an integral plastic pocket clip (on my version) with a hole should you wish to attach a lanyard to carry it around your neck.

The nib is the same as found on the Lamy Safari and Al-star and various other Lamys, available in a range of widths and easy to swap out.
Filling system.
The Nexx takes the Lamy proprietary cartridges or else a Lamy converter.

Writing performance.
The familiar nib is reliable, firm but very smooth as I have come to expect from having used many such Lamy nibs. Ink flow on my particular model is not overly wet but about right. For those needing a wetter flow, it is possible, with care, to open up the tine gap very slightly.

Size and weight.
The Nexx at 133mm is very slightly shorter than a Safari when capped. It measures about 128mm when uncapped, long enough to use unposted, but the cap can be posted quite well, even though the round cap sits on a triangular barrel. Posting brings the length up to about 153mm and is very comfortable. Any worries that you might have about having a flattened edge of the barrel resting in the web of your hand and upsetting your preferred rotation of the nib, are resolved by posting. You can also align the pocket clip with the nib for a visual aid to keeping the nib at your desired angle to the paper.
The pen weighs about 16.5g in all, capped or posted, 10.5g uncapped and 6g for the cap alone.
Likes and dislikes.
Perhaps the most distinctive design elements of the Nexx are its big clunky coloured cap, its rubber grip section and the contrasting aluminium tapering barrel. It seems inappropriate to cite any of those as dislikes. Some might prefer the pen without any facets on the grip and a barrel that did not taper and merge from cylindrical to triangular but these features are the heart of the pen. However, as it is, the pen is very usable even for my left handed writing style.
Conclusion.
A big plus point for the Lamy Nexx, like the Safari, is that it is modestly priced and one of the least expensive “proper” pens available. The price means that you could collect a few different colours if you wish without spending a fortune. It feels strong and almost indestructible and is well suited to being carried around. Above all, it is surprisingly comfortable for long writing sessions. Once you have the pen in your hand, it will not slip. On the contrary, in order to adjust your grip, you have to first separate it from you fingers and then re-position it. It is not a pen that can be rolled around in the fingers.

Whether you find a pen comfortable may depend upon what you have just been using. If that happens to be a pen which has a grip which is too narrow or too slippery, or both, then the Lamy Nexx will feel like a breath of fresh air. It is robust, light weight, and good for long writing sessions. It was a mistake to think of it as childish. Anyone who has avoided the pen for that reason would be well advised to give it a try.