Be careful, picture quality varies at different photo printing locations using different equipment!!!
I've developed pictures at Yahoo and Ofoto (via net/mailed to home) and Costco, Walgreens, Rite-Aid, and Target (walk-in service). All have been fairly good to very good, and compared to my old inkjet printer, the photo process is MUCH better. HOWEVER, the Target pictures (granted, only at one location, so that may be the factor) were of lower quality. Comparing the same photo printed at Costco vs. Target, the Costco photo was nearly indistinguishable from a film camera, but the Target one had noticeable quantization error, visible pixels/digital effects, and some halo like effect around some hair. (Unfortunately, I don't have a simple way to scan/upload the pictures for comparison for you to see).
Each time, I developed batches of about an average of 20 pictures (all 4x6), and these are the results I found (in paranthesis is number of batches and paper brand)
Yahoo (1, fuji?), Costco (3, fuji), Ofoto (1, kodak), Rite-Aid (1, fuji) were all very good, no complaints.
Walgreens (2, fuji) - the first batch was fair, but the second one seemed better and was very good.
Target (2, kodak) - both batches were fair with color problems and unwanted digital effects as described above.
Perhaps Walgreens made some adjustments to the machine between sets, and the Target location I used can improve the quality by tweaking the machine. Or they may just be using a lower quality machine.
My favorite is Costco at 18 cents/print for very good quality, but slow turnaround. What I mean is that these walk-in locations are all "One Hour Photo", but digital prints almost never are, and they don't tell usually tell you that up front. Costco was usually next day service. Target was overnight on one and about 3-4 hours for the other. Walgreens promised 2-3 hours both times, but I didn't return to check, and picked up later. Rite-Aid was great, probably because it was just getting started, but I got the prints in about 20 minutes (waited for them, only one that I waited for).
These are just one person's experiences. I hope that Consumer Reports or someone similar does a nice comparison of the service and photo qualities. Please share any information/references/links on more objective comparisons.