Tbh for that price it should sport a constant f/4 aperture.

Now, not always, but generally speaking; when you’re shooting an event with a 70-300mm zoom, you’d be just as well off whether it’s $300 or $500 with solid autofocus, than all the fancy *#$T canon adds in here.  In fact, when nikon’s 28-300mm (with a more complex design) is sold for $600 less, you have to wonder what exactly canon is charging us for.

Sure, it’s a little bit smaller and has some fancy new age crap they slap on it to sell lenses, but is it really worth $1k over the lower end version with similar af and identical light gathering properties?

Even as an “enthusiast”.  When you’re at the point where you’re spending $1400 on a single lens, you may as well select the 70-200 f/2.8, for almost $100 less.

With a TC, it gives you more versatility than this lazy rich man’s zoom.  Even with the previous 70-300, you could pay for 2/3rds of a 50 f/1.2 with the savings.  

This lens is in the consumer Canon DO club (honorarily of course).