I wrote about the Parker 25 some time ago and I’m afraid that on that occasion I could find little to praise. Several people wrote me to say how fond they were of the pen and this is an attempt to give a more balanced report.
First, there are a couple of things about the pen that I continue to dislike: the ball of the tipping material makes it write like a ballpoint. Also, being a rather slender pen I cannot write with it for long. That said, it does have some rather good points. It is a very simple design with little to go wrong. There are many of these pens around and they always seem to be in good condition. That reflects both the popularity of the 25 over its two decades of production and also how robust it is. The one I have at the moment has a squeeze converter, still working well.
The design either appeals or it doesn’t. I find the barrel rather strangely shaped but that’s entirely subjective. It does post very reliably. The nib has no breather hole. My pen was very dry and I thought that running a shim through the nib would be difficult without a breather hole but that didn’t prove to be the case. The ink flow was good after that.
The pen still closes firmly and that’s true of all the 25s I’ve had. The clip is still quite firm too. It’s a very easy pen to clean. There’s a hole under the feed. Insert something there and pull and the section and nib come out easily. That makes the 25 the ideal pen for those who like to use saturated or iron gall inks.
On reflection, then, I didn’t find it too difficult to find good things to say about this pen. It was in production from 1975 to the late 90s – perhaps 1999. It proved to be a big seller at quite a low price. For those who think they might like a Parker 25, they can be picked up for very little money.
Goodwriterspens's Blog 
I think you’ve hit it on the head Deborah with your comment that you either like or dislike this pen – it seems to have been built solely for function rather than form, and in that sense it succeeds very well, though I’m not a fan.
As with the Vector, this pen needs to be held low down along the section to avoid grasping that irritating ridge at the junction of barrel and section, at least I assume that would be irritating, but that’s more assumption since I don’t write, but others on FPN comment that this feature on the Vector is unpleasant when holding the pen.
It’s a pen I’ve seen commonly on my travels in the past, but they seem a tad less so now – now idea why, but people still seem keen to throw more money at them than you might consider they actually worth.
A small percentage do exist with nibs that sport a breather hole, I have a couple – no idea why this feature should be so uncommon, and likewise you have to acquire quite a few in order to find a range of nib/tip widths.
Having made it clear I don’t really care for this design, can say I do currently have ten of them, including one of the legendary white ones – but that’s what happens when you’re a collector and not a writer:-):-)
However, if you want a apace age all steel pen, then the 25 is a must.
I think I’m right in saying that the very first ones had a breather hole and it was dispensed with afterwards. There’s one with a green section in eBay at the moment. The seller says it’s very rare. I don’t know.
I tried to like this pen but the thing that repels me is the nib. If it was a choice between a Bic ballpoint and a Parker 25 I think I’d take the Bic.
:-):-) I suspect that I’m just the wrong age for such a modernist type of f.p.
Maybe. But it is about 55 years old…
for those interested in such things, the green sectioned example mentioned by Deborah changed hands for Sterling seventy three pounds plus p. & p.
I use a Parker 25 as my take anywhere pen as it’s practically indestructible & totally reliable. It writes very well & I hold pens near the nib anyway. I use it in the field, literally, to make notes along with a Jotter or a land inspection app. The styling is very much of its time which I like but then I’m older than the pen. The Vector by contrast is not as good. The plastic barrels tend to split through the threads.
Unfortunately I’m older than the pen too. They’re certainly indestructible.