I had the I-4 medium and while I used it for detail work w/ brushes etc. I didn't like it for general use and found the mouse faster. In addition, I was wasting most of the drawing surface because for photo editing I didn't need or want all that real estate.
Enter the I-5 touch small! This thing is truly a game changer for me. Adios keyboard (for the most part), just the right amount of area, wireless (w/ the additional wireless kit), and it is very usable as a versatile touch pad so that I find mysel reaching for the mouse far less often. I have a feeling after a few weeks of experience with it, it will become an integral part of my workflow technique, rather than the mere accessory for fine detail work that my I-4 has been. Truly a leap forward from Wacom.