Unsure as to whether this program would be useful or not, I downloaded it to test it, something I seldom do. A minute of frustration in trying to get a watermark in place was quickly over when I looked at the Help file, which detailed the process nicely. One warning, your watermark image better be nice and small or it will rival the image you are trying to watermark. (You can use this same program to scale it down.) Had a good laugh about that!
Without any more fuss I was able to watermark and scale images in under 5 minutes, so I hurried back to MacUpdate to purchase EasyBatchPhoto. I think I'm going to be using this a lot. I haven't tested out all the features, or long enough to test stability, hence the moderate ratings for those.