Image import is easy enough, from Apple Photos and loose images in folders. Haven't tried devices yet (cameras, etc), but that's not my focus.
Basic editing, browsing, tagging, all seems familiar and snappy.
The app itself can be customized within reason, from overall look to picture display. Finding an image by date is neat, and so is creating albums, managing events, etc. At first glance, the app feels mature enough to manage pictures -- something Apple doesn't seem to want to offer anymore. From the point of ease of use, I give this app praise.
There doesn't seem to be a way to use the app without giving them your email and letting it connect to the internet. If I was interested in online-features, I'd say "ok", but I don't want to share my data or metrics with Mylio, and I don't let my production setup connect to the internet. Looking at the programs console and Little Snitch, Mylio wants to connect home quite often (mostly during import).
I have more than 25k images, which means I either use the mobile device version (nope), or pay a MONTHLY FEE. I see no pay-once-and-done option, and I am not going to shell out about USD 250 per year to manage only 500k of my images (or about USD 100 for 100k images, or nada for just 25k). I cannot fathom what causes the difference in the number of images (which, reading forum posts around the web, had been increased in the past years, leading me to believe the limit is arbitrarily calculated). My various collections combined are way over the 500k limit (which Apple Photos can handle). I wonder what happens to my images if I stop paying, the company goes under, or [insert event here]. Yes, I could store more images without paying top tier, but I do not want them on my iDevices, where space is rather limited.
You also pay for RAW stuff and Lightroom integration -- again, monthly. The same counts for the ability (!) to connect to a cloud service (which you have to pay separately).
I understand that programmers need to get paid for their work, perhaps code licenses, administrative and online distribution costs (oh, and good marketing). Make me pay once, charge me for pro stuff, let me pay for upgrades down the road.
So far, this program looks promising for the casual user, not if you have a rather large collection of pictures to manage (even semi-professionally).
This relates directly to me disagreeing vehemently with a subscription model for desktop software capabilities (I agree with subscriptions for a valuable service, like online file storage, news services, entertainment, etc). The world may be moving towards a subscription industry, but I contend this to be the works of marketing specialists and not end users.
The only use I would have for this program is image management, and it does so rather well, already so much better than Apple's Photos.
Again, if you are a casual user with mobile devices, this program sounds fantastic. Every collection grows, so keep the file limit in mind.