I just experienced this rather tough decision myself. After a side-by-side comparison in the store, which offers less-than-ideal lighting conditions, I went with glossy. My eyesight isn't the greatest and I found that the extra sharpness offered by the glossy screen made it easier for me to focus on small text and fine detail. It also had ever-so-slightly better contrast and richer color.
On the other hand, it wasn't an easy choice. The new matte screen is a lot better than the previous one. I always felt the MBPs had a somewhat dull/grainy look to them. But the 15.4" matte I evaluated today was smooth, bright, and crisp.
Please note that this only applies to the new 15.4" displays. I didn't take the time to look at the 17" model.