Well, maybe not changed me, but this ink was well worth the cost! My most well-used pens are a Hero 329 and a Foray Focus. I've been using Parker black quink, which has been ok. (I got it as part of the sale when I bought some of my pens on the BST last year.) It isn't all that...well, black. It also will smudge and smear very easily if the paper gets wet at all - not that great of a trait as I tend to drip coffee from time to time.
Enter the 5 O'Clock!
Both pens write much better - the 329 especially. The nib doesn't really flex by any stretch of the imagination, so I don't get any vibrant color gradient. However, when I'm looking back at samples of the quink and 5 O'Clock side by side, the 5 O'Clock is much nicer looking. It's very black, but there's just that aura of green that shows up every so often. I love it.
Now if I could only master Spencerian and get rid of this darn chicken scratch!