Still using Aperture as an integral part of my processing chain. I've not found an alternative which can do the skin smoothing and retouching job anything like as efficiently, using the Imagenomic Portraiture plugin. LR would do it, but I don't get on with Adobe's interface. (As in I hate it so much it causes me physical pain every time I try use an Adobe product).
C1 is getting there; the retouching step is not as efficient (important when selling 2000+ retouched photos per month) but at least it works as a fallback. Still need Phocus because Phase decline to process Hasselblad images (which is their commercial right but which remains a pain in the arse for customers).
I just updated my "spare" old MacBookPro to 10.13.3 and all seemed well; just updated my "production" MacBookPro and edited a set through it, seems to work. I haven't encountered any of the minor niggles others have reported. I might be brave enough to update my production desktop machines in a week or two.
However, what definitely doesn't work is processing newer camera images. Downloaded an A7Riii RAW file. OSX can see it fine, as can C1, but Aperture gives the dreaded triangle of death, image file not recognised. Fudging the EXIF information via Exiftools to make it think the images are A7Rii works, but clearly this puts Aperture on borrowed time as a RAW processor

So long as it continues to work on TIFFs, I might keep using it as a one-purpose tool: do the RAW conversion in C1 or Phocus, import the TIFFs to Aperture, Skin Soften with Portraiture, retouch and add a few little polishes (e.g. I much prefer Aperture's Gamma vignette to most other vignette implementations, and its vibrancy control is really nice and subtle). Then final export to the JPEG sale versions from Aperture.
It's not ideal compared with doing everything in one program, but I've been doing TIFFs in Phocus -> Aperture for years and have got a decent workflow going.
But damn, I wish Phase would look at reducing the number of mouse clicks needed to brush heal and brush in skin softening. At this rate Hasselblad might even get there first - Phocus gets notably better with each release.
Hywel