Photomode is beyond awesome as long as you play with premium cars. The free range camera is like the best thing you can get. I was worried about the camera not mount on the car when I saw some poor panning shots by others. Once I checked out the camera menu, there were 3 options of panning. The 2nd and 3rd moves along with the car when you focused, so GT5 curve blur is guaranteed but you need a car can corner fast, because 1/60s shutter speed isn't slow enough (check out this page for details
http://us.gran-turismo.com/us/products/gt5/photo/)
One thing you won't be happy is no colour adjustment whatsoever (no manual WB and no saturation). You may play with those fancy filter, but no way you can make half saturated photo without photoshop. There is an AE lock available, but not really sure how I can take advantage of it, maybe useful to stitch multiple images for panorama?
Tilt shift filter is totally a gimmick. It just blurs the top and bottom quarter of the photo, and it is not based on focal distance. However f/1.0 is handful to most situations. Vignetting option is gone in photo travel, but it automatically builds up when the shutter opens wide (f/1.0-2.0).
Camera angle now can be fully adjustable. You can shoot the sky/ground straight (hint: mini-planet 👍 ). In photomode (not walk mode), there is no control to move forward/backward, but you can go sideway. You would need to rotate 90 degrees and move sideway in order to move forward/backward
... beware of seizure!
Walk mode is simply let you to move the camera position, while photomode let you adjust everything you need for a photo. Good thing is both mode allow positioning the car (photo travel).
Saving photo is quite fast, but it is pain in the butt to export them to XMB, because there is no batch function.