I use Microspikes in the White Mountains in the USA all winter. I recently bought crampons as well, because I gather I’ll need them for some hikes I’m doing.
Microspikes are great. If you’re (very) careful, you can (just barely) walk up 30-degree transparent ice (not measured; may be steeper!). But if there’s any exposure, I wouldn’t. I have _not_ tried to get up in microspikes after an ice-axe self-arrest; I’m not sure how much harder that would be without front points, but I’m guessing it would cause problems—you might even have to do a self-arrest fall down to somewhere where you can stand up again, so, um, yeah.
They are, as others have said, highly effective, half a kilogram lighter than crampons, pack small, are unlikely to puncture gear in your bag, go on and off easily and quickly, and they pose little danger to the user or even those around you. Maybe get them, and carry both on some non-critical hikes?
My microspikes are older, and have performed flawlessly. I hear the quality at Kahtoola has gone downhill lately; Hillsound seems to have some really good-looking products in a similar weight range, but I haven’t used them.