First off, 28 quarts is rather small for all grain. I have a 30 quart turkey fryer pot and I find it to be just a little too small. However, 1650 watts should be plenty to get a good boil going rather fast. Also it's nice that there is a a built in valve for draining the wort.
In summary, seems like it would be a good for doing 4.5 gallon batches.