I personally haven't used it, but even for the price, I believe it is worth it.
For me, it seems the aperture doesn't matter for this lens, there is something else.
The hybrid is is amazing, I have it in my 100mm l macro.
Also, it does macro.
And also cano bumped up the price, because they had to shave down the lens to put it in that small package. A lot of architecture went into the lens.
If I want a 24-70, I'll go for this lens over the old f2.8. But also, the tamron is an option, or if you can't justify the price, look at the sigma 24-70's. the new one is the canon 24-70 f4 size, and the old is huge, but cheap.
Hope it helps