Overall speaking, if I were looking for an alternative to Google Analytics, this would be my first choice. But if you rely heavily, like myself, on Google's tools, you might find easier just to use Google Analytics. Piwik is a lot more transparent, cleaner, easier to use as a standalone tool though.

I loved the way information is presented to the users. For some aspects it's way clearer and more intuitive than Google Analytics.

While Google Analytics belongs to the same ecosystem as many of the other tools (Google Ads, Search Console, remarketing etc) you would use if you work in digital marketing or you need to get an idea on the data related to your website, Piwik doesn't belong and this makes harder integrating it with other tools. Also, I had some issues when using Piwik in terms of impact on loading and data retention (disk usage was growing exponentially when one of my website ramped up).

I really like the interface and the data visualization tools.

Simple and beautiful interface. You can have all the information about your visitors. I really like to be able to know if a visitor is coming back or if it's his first time visiting my website.

Creating custom events for particular actions is a little bit limited because you have to classify them in categories and then it's difficult to get stats from those categories

an Analytics product that complies with EU privacy laws (that's really the primary USP compared to GAnalytics I think)

That you can install it on your own server and the data is saved in your own database - you you can comply with privacy and data protection laws (especially in the EU).

Offers not so many features like Google Analytics, the web UI is quite slow, not so easy to understand how to go beyond standard features, the mobile SDK could be better

Piwik pro offers a great solution for all types of business trying to keep up with analytics tools. The tool is complete with an analytics offer, but a consent management platform and a tag management system too. Servers are located in EU, which is GDPR compliant

The tool is still in roll-out, and some features regarding the tag management system of Piwik can be outdated for big companies

Privacy protection and it's still possible to store and analyse data while complying with privacy regulations (RGPD). Nice customisation options.

Needed technical help for the initial set up, so take some time to be confident with it.