After a lot of review reading on the internet and bouncing back and forth between breaking the bank on a Canon 70-200 2.8 Mk2... I decided to go with the 50-150 for the following reasons.
1. On crop it provides similar field of view as 70-200 does on full frame. This removes some of the awkward focal length that you get when using a 70-200 lens on crop. I really enjoy being able to use the 50mm wide end, although can still feel crowded at times it provides versatility.
2. The price was insanely good and comparing it's cost to Sigma and Tammy 70-200 2.8's with OS or VC it was better priced and since neither one are true 200mm lenses it only made sense to go with the 50-150 as you gain wide end and don't lose much long end.
3. The zoom and focus ring move the same direction as Canon lenses. Not a huge issue but makes it easier to adjust and zoom without having to think or break muscle memory.
Like most other reviews I see posted the lens was razor sharp out the box and to my extreme surprise does not appear to require any micro adjustments for focusing!
The focusing is sharp and silent. Although everyone notes that the OS is loud, I never would have noticed until I listened to it. It might be louder than Canon IS, but overall it isn't loud per say. Focusing is fairly fast, slower than the better Canon USM lenses but not by a lot.