Yep! I have a small collection of Wonderswan games and a few consoles.
The screen on the WSC is truly terrible, one of the worst colour screen I've ever seen - it's near impossible to see under normal lighting conditions. Pop an IPS in that bad-boy and it becomes much better!
I'd say Wonderswan is probably one of the least friendly to collect, since not only are all of its games in Japanese (Bar one - a digimon title which has a full english translation) , the majority are RPG or otherwise text-heavy games so it's somewhat lacking on the games you can "just play without reading".
That said, there are a few titles out there that are worth having a look at. One Piece Grand Battle Swan Colessuem is a solid fighting game based on the first few arcs of One Piece, and Digimon Battle Spirits is another one which is a fun fighting title (Which was later ported to GBA I think), and the sort of rhythm-platformer Rhyme Rider Kerorican
There's also some cool strategy titles out there, like Blue Wing Blitz (WW2-style dogfighting turn based stategy with a FF:tactics style aesthetic).
It's a quirky console. The hardware is actually pretty powerful, and the fact that it runs on one battery is impressive! Just a shame the library isn't particularly diverse.