I mean, it's nice to have the ports, but you have externally power the drives because the PSU is 3A, so one for the computer and that leaves 2A. Most HDDs need 2A to spin up so you can only have one drive. So no redundancy.
If I was to make a NAS (which is what I would be interested in) I would pay triple for something like the NAS killer 6 [3]. To be fair the Zimacube might be more of a challenge to this (but its not out yet).
I think its interesting though for a small, fanless sever. But (understandably, it's cheap) if you wanted something more, an extra $200 would be get you much more. I guess it depends on what you are looking for.
So Kickstarter compute blade which is not shipping yet, zimacube which is not shipping yet, or build-your-own for more money which is not really the same category as the zimaboard. Those are not great alternatives today.
Zimaboard came out of kickstarter a year and a half ago. Patience is a virtue.
Another reason why there aren't that many alternatives is that you can't use it for that much. It's like buying a car that can carry 50 kg. Great if thats your use case, but if you want anything more, there's no point. I can't really use it as a NAS, firewall etc. I think it certainly has uses, they are just ones that the average NAS/server people can do with a stronger server that can also do nextcloud, pi-hole, etc, in one, rather than have a device for each (which is way more costly).