I've had quite a few grinders over the past few years including a Mignon(50mm), Atom 75 with SSP, Niche Zero, and Comandante.

The Olympia Moca has the same "feel" as the Cremina and the Maximatic, in that it's heavy, the case is metal, the hopper is very thick glass, and the cap on top of the hopper is machined metal. When I looked at the photos I wondered whether the adjustment knob and the collar that connects to the hopper were plastic.. but no, all steel or aluminum.

I can't speak much to the motor, but I believe it's a 300W, off the shelf part, but it has seemed powerful enough to do the job.
I have read others complain that it doesn't grind fine enough but it certainly does. The range of the adjustment knob covers a relatively small change in grind sizes.. but they include instructions that tell you how to remove the knob cap and set it to a finer or coarser range. During the first two weeks, I found myself grinding finer and finer as the burrs seasoned and then I had to make the adjustment to a finer setting (a really simple thing to do with a hex screwdriver)

So there is no problem with grinding very fine, but it's clearly designed as an espresso-only grinder. There's no easy way to move from espresso to filter and back.

It's also clear that they expect you to fill the hopper rather than single dose, and I did that for awhile. Eventually I decided to use RDT and single dose anyway. I found that this works fine, but the Moca wasn't meant to be a zero retention grinder, so expect to purge a few grams of beans whenever you change beans or grind settings. I also find that the static can make some mess unless you RDT.

As far as grind quality goes, I'm really happy with it. Taste-wise I think it stands up well to anything I've had before, and I prefer it to the Niche. I did a few informal side-by-side tests and both were very good but I just tended to prefer the clarity from the Moca, but others may have different opinions with different beans.
I never had a chance to do a side by side comparison to the Atom, but from memory, no huge taste differences jump to mind. But, the Atom had much less static, ground faster, was quieter, and the grinds were visibly very fluffy. The Eureka grinders also get points for being easy to disassemble and clean. I've seen videos online about taking the Moca apart and it looks like a project. Finally, I don't want to say the Moca is loud, but there is certainly no attempt to dampen the noise. Every other grinder I've owned was quieter.

All of that said, I really like the Moca because it's so small, the taste is great, and aesthetically it fits well with Olympia machines. I don't mind purging a few grams when I change settings, and, aside from that the grinder has been very consistent: by that I mean that once I dial in a certain grind to espresso yield in 25s, the shots have been repeatable. I also really appreciate the high quality metal and glass parts (the plastic Eureka hoppers always irked me on what were otherwise such great machines).

And of course, everything depends on what you hope to get out of it. I tend to like medium roasts and so 65mm flat steel burrs are fine. I have a feeling that if I begin experimenting with lighter roasts I'm going to be wondering what I'm missing by not having a Ditting 807 or a Monolith Flat.