If you're a fan of early 90s house and old school jungle/hardcore, this is an absolute must have. I've spent a shit load of money on VSTs and sample libraries over the last two years, and the $50 I paid for the M1 are easily among the most well spent. I'm just having so much fun with it. I don't necessarily use it for final productions, but it's quickly become my go to synths for sketching ideas. Sure, the sounds are absolutely cheesy and overused, but I find them very inspirational. Everything sounds familiar and all you need is right there in one place. You've got you're cheesy string and synth pads, cheesy bass and lead synths, all kinds of other cheese, and, of course, the famous cheesy pianos. Just add some drums, mess around a bit, and you've got yourself a track.
I'm not a big synth nerd, so I can't really tell you much about how the M1 stands up to modern synth technology. But I openly admit that I only got the M1 for the presets and the nostalgic feel. And for that purpose it's just perfect. So I'm giving 10/10 for the fun factor, the ease of use, and the very affordable price.