I just did a test on using the exif information from geotagged photos for mapping. This time, I set my phone (Samsung GT-S5300) to add the location in the exif data. Using the same phone, I also logged my tracks as a background process with GPSLogger.
The image below shows the image location in JOSM using the exif's lat/lon data. The GPS trace is also shown. Notice that the photos are arranged in a grid-like manner and does not entirely correspond to my tracks.
Using the traditional photo to gps position correlation in JOSM, the photo location is way more accurate.
Just to test if this is a JOSM bug, I tried reading the photo's exif tag in QGIS using the Photo2shape plugin and it shows the same grid-like position in the first image.