Excellent, but...

AdamT wrote:

its weak spot is edges (at least at F5.6 and smaller at the wide end)and sample variation , this one is usable through the zoom, some are soft at 45mm, some have edges like a Holga . whether there are ones which are both sharp at 45mm AND have good edges at the wide end is another matter , I`ve not used enough of them to find out ... the lens is also very fussy about where a landscape is focussed for edged and if the IS unit has settled down (Both can cause blurry edges)

Yup, there’s a fair amount of field curvature inherent in the 15-45’s design (it’ll be present in all copies). And you’ll see moderate mustache distortion at the wide end. Canon’s DLO corrections help with these, but good practices in the field (as you mention) also help.

The 15-45’s big fault is that darn decentering that folks should look for when they get a new lens, and then exchange for a different copy if it’s bad. I’ve speculated that the (assembly) mold/jig was at fault, and Canon should have been tossing way more of these sub-par lenses during their QC process.

I’m going to (hopefully) be able to give my copy of the 15-45 a good test this evening (an architectural shoot). It’ll be the only lens I’ll be taking, which will force me to make the best of it (it’s how I like to test when evaluating equipment - sink or swim! ).  A couple of years ago my first 15-45 actually acquitted itself quite well when I selected it (and my M5) for an important mountain bike shoot (a great test).  I was really nervous about leaving my DSLR behind for such a fast action event, but that was the day that I realized mirrorless had finally come of age!  

I feel bad that the OP’s lens is giving him trouble. I wish he’d post some samples so we can get to the bottom of it!

R2