I was lucky enough to win a set of these in one of Tiger Pens' monthly giveaways.
Although I use fountain pens for most of my writing, you can't beat gel pens for writing you need to dry quickly, or that you want to stand up to the elements (I use a Parker Jotter with a Parker gel refill for addressing envelopes, for example).
That leads me to a rather limited palette of blue and black, so I was pleased to be able to try a greater range of colours.Ink Tests (Paperchase Kraft Notebook)
As you can (hopefully) see, the colours from the Zebra pens are vibrant and consistent. I've included a few fountain pen inks in the lower part of the page for colour comparison.
My only slight disappointment was that the Orange pen came with a black refill - as the pens were free, I'm not going to complain about that, and I'm sure it wouldn't happen in a purchased pen.
The speed of shipping from Tiger Pens was impressive - the morning after I sent them my mailing address, the pens were waiting for me on the doormat!
The pens write pretty wet, and I was fairly convinced that this would lead to them "blobbing" at times onto the page, but that didn't happen at all.
A Test Sketch (Cheap Spiralbound Sketchbook)
I put them through their paces doing a quick sketch inspired by the "Zebra" name, and found them pleasant to write and draw with - smooth (except for when I put them at too low an angle to the paper - I assume that's the "cone" aroud the rollerball tip "catching" on the paper) and the line stays consistent. The line they write is pretty broad, but I like that, preferring a fibre tip pigment liner for *really* thin lines, and I really like the brightness of the colour. My personal favourites are the blue (lovely and deep) and purple. The black writes a solid, properly dark black too, reminding me a little of Herbin's Perle Noire, my favourite black fountain pen ink.
Despite the pens being retractable, they feel solid in use, without the "rattly" feeling some retractable pens have. The only criticism I'd make of the mechanism is that it's a little too easy to activate - my Jotter requires more pressure, and is less likely to end up ready to write when being carried in a pocket! You could reasonably point out that it's silly to carry retractable pens in a pocket (that's why they have clips!) and I'd not disagree with you - I'm used to capped pens :)
Whilst gel pens won't win me away from fountain pens and ink, there are times when you need to write on less than teriffic paper, or write a label or address that you need to be waterproof, and these pens fill that niche for me. Gel pens are a bit more pleasant to write with than ballpoints, and it's worth keeping one or two (or eight if you like colour and/or are indecisive :) ) around even if you're a confirmed fountain pen addict.
The pens are currently £2.34 each at Tiger Pens, meaning the full set of 8 colours will cost you £18.72 - although I've not tried them, you could also consider the Uni Ball Signo 207 RT, slightly cheaper, and a similar range of colours at £2.10 (but no pink!)