300 f2.8 is USM MK2

Bought the latest (and greatest?) Canon lens, the new 300 2.8 prime. I had the old one and lots of Canon zooms, so is it worth the very high cost? Well, first the good. You really feel the loss of weight. It is handholdable but a monopod is advisable. The four stop IS really is four stop. It works amazingly well with the new mk3 extenders to. What really shines are two things. Get a top pro lens then get a top pro body. On my Mk4 the autofocus is lazer fast. Less so on other bodies. But the image quality is better than any other lens ive used including my 500. It has an X factor I just can't describe. If you own a 100-400 or even 70-200 and rent a 300 you will be blown away by the quality. You will notice a step up. The bad? Cost. Well you want the best dont you? The image quality whilst more punchy than the old , more contrasty, isn't any sharper. It's just less weight, better I.s, faster autofocus but not a massive change. If it were me id rent one, rent an old one then decide. Is it Canons best? Yes. No ifs or buts. Yes, it's that good.