Lol, thanks for bringing them up. Just realised I have 1 share there, bought in 2013, the entire 0.1GHs (I was new to bitcoin back then and was just testing how it works). Completely forgot about them.
Anyhow, I'm pretty sure they're not ponzi as they've been around for years now, operating quietly without hype, advertising etc. But don't think their prices are really attractive (too lazy to compare to others).
And I'm a bit surprised they're still running the first, ancient miners (i.e. "antMiner Rig (12 units total 2280GH/s)"). How's that still profitable? As per T&Cs, they are supposed to sell unprofitable miners and divide any income among the holders of shares.
Edit: Just checked dividends tab and looks like the payments were made consistently on time. Also my 0.1 Gh/s rose to 0.13 Gh/s, probably due to hardware upgrade.
Edit2: Didn't even make 50% ROI. But that was mostly due to the massive pump + diff increase