My first impressions were a bit negative, as I was expecting "open source Dropbox" and nothing more; Nextcloud actually does quite a lot, which made me think it was bloatware. This is due to my ignorance and jumping in too fast.
What Nextcloud actually is: a personal Dropbox-style server, with open source equivalents of Google Docs, calendaring, contacts, notepads, and a complete "app store". It's all really well built, and you can use as much (or in my case, as little) as you feel like. I thought I'd use none of these apps at all, until I realized that I would really like a Del.icio.us-style [bookmarking app](https://apps.nextcloud.com/apps/bookmarks), but had no desire to shop around and adopt something that required a fee or might disappear later.
At this point, my only criticisms are that I think the installation should be more idiot-friendly, and the UI smells of 2012.
For anyone interested in following suit, I picked up an [Odroid-HC1](https://www.hardkernel.com/shop/odroid-hc1-home-cloud-one/) (a bit like a Raspberry Pi, but much higher disk and network performance, at a similar price point) and [NextcloudPi](https://ownyourbits.com/nextcloudpi/#download) (complete Debian + Nextcloud image). It went swimmingly and cost well under a hundred bucks, not counting the 3.5" hard drive.
Nextcloud is backed by a corporation that mostly makes its money off support for the German gov't? I think it's an ideal solution for any municipality, non-profit, or small-to-large sized company that for whatever reason doesn't want to go with a commercial cloud.