I think they are fine for hardpack and ice on relatively flat surfaces. I could not get up an icy hill on them to save my life a few years ago. Not enough studs or at least not enough studs in the right places. I didn't find them to be very good in the snow either. They are sold in two different widths. Maybe the wider ones are better.

One thing I've learned on these forums though is that people often have wildly varying experiences.