This is a great little product with one serious, annoying flaw. It prints extremely nice 4x6 borderless prints, with excellent color, but even if you send it a picture that’s been formatted to be exactly 4x6, something in the driver or the printer itself is increasing the image size slightly and cropping about 1/8th of an inch on all sides.
This is actually the same behavior people have been getting from traditional one-hour-photo prints for decades, but when you have complete control over the cropping on your computer, it’s a damn nuisance. It’s even more annoying when you’re printing out documents with narrow margins or pictures downloaded from the web.
A quick Google suggests that their tech support folks are clueless about this issue, and don’t actually understand the complaints they’re getting about it. [Update: those complaints must be old. I got a clear, correct response within a few hours. Sadly, it’s a “working as intended” feature, and they don’t mention workarounds]
My guess [confirmed by tech support] is that they’re fudging the image to cope with misaligned paper, so that a supposedly borderless print doesn’t end up having a border on one side. I’m going to create a numbered 1/16th-inch grid in a PDF file and see precisely what ends up on the paper.
Update: Printing this PDF (created by this Perl script) at various magnifications reveals that 95% is just about perfect, but small alignment errors may produce a tiny white border around the edge of photos. The print driver has some adjustments for paper positioning, which should allow you to get perfect, uncropped, full-bleed prints at 95%. Mac OS X applications that use the standard print dialogs should all work with this, including iPhoto.