it is a great lens for sure... you posted in the macro section, so you might not get the full scale of answers you are looking for.
Obviously, for macro, it works great.
I can say that I use mine for portrait as well and it is great to work with. It is very sharp wide open and the AF is very precise and fast as well.
I have used it a couple of times for landscape, cannot complain.
But indoor for kitty cats, might be difficult, it is a 100mm afterall. I suppose if you want to do portraits.
Not sure what kind of macro you want to do, but you could consider the EF-S 60mm, much cheaper, it is insanely sharp and great focal length on a crop body for portraits.
Martin