I've had a PS4 marius board for the last week and I can honestly say this thing is insanely nice and snappy to use. Everything I do is immediate, every stick direction, every input. Really enjoying it!
It's quite hard to explain how nice it feels, I guess my comparison would be going from 144hz to 240hz for a monitor. The difference isn't immediately noticeable but when you go back to that lower 144hz it suddenly really highlights how much nicer and more immediate 240hz was.
Would only recommend it for competitive FPS players, it has no rumble, no battery, doesnt work on console, no bluetooth, no touchpad tracking and no audio jack (that's a lotta no's!). I bought a DIY kit for it and it wasn't too much effort to solder it all together with an existing PS4 controller I had.
I have ordered a Tarantula 8k which should arrive in the next week or two so it'll be a nice comparison. Especially when the Tarantula was 79 quid vs. the DIY kit for the Marius Board costing me 150ish (and then needing a PS4 controller already).