Innovator

I sold my 200 f2.8L & 135 f2L in favour of this lens to have more flexibility (even if those were the almost perfect primes Canon ever made).

First I was a purist with Canon's Holy trinity (85L - 135L - 200L) which I planned never to sell, but I found for the longer focal lengths primes not so handy.

The 200 2.8L was too tight (even for basketball shots out of the tribune) on a 5D2. The 135L was better, but as I ocasionally shoot basketball I didn't want to keep this lens either. I had the 135 f2L on my 40D crop and with the 1.6 cropfactor, the 216mm was an awkward range.

I wanted to give my 135L a second chance on my 5D where 135mm is 135mm, but as I have the magical 85 1.2L I eventually sold the 135L also.

85mm is better for portraits. The 135L would be great for candid portraits, but you need to have a lot of moving space for this. I would mainly use it for onstage performances (on seat), receptions, basketball (on seat), in 3 situations almost impossible to take steps behind.

So I compared all 70-200's and the f2.8 non-IS seemed sharpest, best price (I only paid $850 to a wedding photographer who sold it for the 70-200 f2.8L IS II).
He showed me some pics from his children and some wedding albums with this lens, all great with f2.8 bokeh.

The 70-200 f4 IS is also great tack sharpt, but it's a "sunny lens", I don't like f4 (you never know you have to shoot inside, that's why I sold my 24-105 in past).

So the 70-200 f2.8L non IS replaces my 135 2L + 200 2.8L and is ideal for events,concerts,... always flexible/lowlight/sharp/bokeh advantage.

The 70-200 2.8L is a perfect follow up on my 28-70 2.8L
Both 2 elder gem lenses, but great IQ, price,...

The only 2 primes I have left are the 35 1.4L + 85 1.2L
Those two are magical primes and can be used more often due to less mm's.

Now I have my perfect setup :
35 1.4L + 85 1.2L (bokehlicious lowlight portraitprimes)
28-70 2.8L + 70-200 2.8L (best allround zooms)