I have been a user of primes for some time now and was then introduced to this beast of a lens. It is true that this lens is not only very large with its 77mm filter size but it is very heavy. This was my only major gripe about this lens because otherwise it is very fast versatile and awesome lens. The 24mm is more than wide enough on the full frame sensor and the 70mm is great for the tighter portraits. The fast f/2.8 aperture through the focal length is great to have in place of switching lenses or bodies while shooting. It is of course not as fast as any of the primes out there but you'll have to be the judge of whether or not this is a sacrifice you'd be willing to live with. The bokeh is rather pleasing for a zoom lens and the autofocus is very fast and accurate. I have used this lens now for a month and now do not want to give it back as it was borrowed from a friend. I still love my primes, but this lens has now opened my eyes to new possibilities.