It depends on the photo. If I can see the product, or the point the reviewer is trying to illustrate (for example, focus doesn't need to be absolutely perfect to show how close something is in size to a bottle of Coke), then the photos are helpful.
If I have to bend my neck 90°, cross my eyes like I'm looking at a stereogram, whip out a magnifying glass, or if the photo is grossly out of focus or too dark, then it's not helpful.