The pro of the fertilizer is it gives you a general high/low level the big downer is it can't warn you if you're off balance.
Basically all fertilzers have 3 core values xx-xx-xx nitroget, phosphate, potasium as I recall some plants require different balances. Easy bloom just says high/low so make sure you use the proper fertilzer with the proper plants and easy bloom's rating is useful, just "winging it" could cost you a plant. (though I believe easy bloom would rate your fertilizer as too high in most such cases)
(Basically generally fruit plants excluding citrus 15-35-15 fairs well, leaf plants like lettuce, cilantro, etc a balanced blend works 10-10-10, obviously there are tons of exceptions so look up your plant and see what others recommend)