I may be biased as Peter’s stuff is the main reason I got into Euro stuff at all, but I really love it.
They are surprisingly versatile. As in, if you want normalish VCO/VCF/VCA type voices, you can get that. And obviously each module has a bunch of idiosyncratic craziness. The Denum was a late/recent addition, and I have to say I really love it. The built in VCAs in Denum/Dunst are both really interesting in that they are bipolar with a built in comparator. With just those, most of the patching I’ve done so far has used the Bubblesound quad VCA as just a mixer.
Each module is also super deep too. Sprott sounds good, and gives you lots of filtering options, but there’s so many variables and CV stuff, that I haven’t scratched the surface at all. Similar for Swoop. Fourses is complex too, but it’s an old idea of his, so I feel like I’ve been around that sound world and concept for years.
Priority-wise I’d go with a Fourses, then Swoop, then maybe Sprott, with Dunst last. Also depends on what you want it to add to your system.
If you have any specific questions, I’d be happy to answer them.