I last looked at Pic Scanner last summer, and found it barely better than snapping a picture with Apple's camera app. Pic Scanner could do multiple photos but there weren't too many features, and the free version wasn't very flexible. If you wanted to share an image, you had to make a in-app purchase of US$2.99.
Here's what the app does: Put some photos down on the table, and group them close together. The app takes a photo, then auto-crops so you have each photo as a separate file. There are filters, like sepia, black and white and others, and there are enhancement tools like sharpen and tonal balance.
Thing are much better in this new version. The app is still free, but still limited in saving and sharing pics. You can now scan 10 photos or groups of photos, up to four at a time, and share three times. Then you need to buy the app, which for March only is $0.99, a much better deal.
This new version makes higher resolution scans on the iPhone 5 and 5s, and there is a sharpen filter. Four photos can now be auto cropped instead of three, and the app integrates with Google + and Dropbox.
The app offers a new spirit level to reduce distortion in your photos, and the whole app has had a pleasant re-design for iOS 7.
I tried the app on some really old, low-resolution photos I had taken in college with a crummy film camera. The app accurately cropped each photo, and the enhance option did balance the color a little better, and sharpened things up. The developers suggest placing your existing images on a white background before snapping them with Pic Scanner, and that's good advice. On a wooden desk the app had problems cropping and auto selecting the photos, so I just put everything on a piece of white printer paper and everything worked well.
Pic Scanner isn't as effective as a hardware photo scanner. I used my inexpensive Epson XP-400 scanner/printer and got a better quality scan, but then I needed to get that scan into Photoshop to clean it up and color balance it. It did a better job, but at a much higher software/hardware expense.
Pic Scanner works as advertised. The universal free version will let you see if it will work for you, and I think for many casual users it will be just fine. The free version gives you a little more latitude to experiment, and if you have to buy it's a much better deal at $0.99.