I got a tattoo in purple, white, and light blue ink in early June, and most of it looks really good, only faded a little bit. but the blue was almost all gone within two months of getting it.
i get a free touch up so I'm not super worried about it, I'll probably ask my artist to go over it in a different color.

but has anyone else had less than positive experiences with blue ink?

blue is known to be amongst the most stable and bio-compatible inks, as far as being the most recommended ink for getting your eyeballs tattooed; you probably just had a bad expericne with a bad brand and not with the blue ink itself