I always read on the Cardboard Warriors forum about how paper minis printed on photo paper look better, and even though I was interested in trying that, I can only find photo paper in very expensive bundles of lots of sheets. A couple of months ago, one of the forum regulars (Parduz) posted about using a photo printing service and that stuck on my mind. Recently, I found a place where 10x15cm photos may be printed at a low price, so I finally managed to get some miniatures done. Here are the first results, from Darkmook's Surival Horror set 6 (Unstoppable):
As one might expect, things aren't perfect, and there are some downsides as well. Scoring the paper so that it folds properly requires using more pressure than with normal cardstock so that you almost cut the two halves apart. Less than that, and the paper behaves like a spring, making the gluing process a nightmare.
The glue stick that I have been using very successfully also didn't work with this paper, so I had to get back to spreading thick PVA with a brush. I also found necessary to burnish the glued sheet well and leave it to dry under some heavy weight for hours before cutting. I didn't try spray mount on these, maybe that's a better solution. For the above reasons, my attempts at making tabbed bases in photo paper (shown in the first picture) didn't go so well and I don't plan on doing that again.
After this test, my opinion is that printing on good cardstock already provides good-looking and useable miniatures. Using photo paper (especially if using a good printer or print service) gives them a more distinguished look and thus could be used for player character miniatures in RPGs or special units in strategy games.