I've been running these tires for a (snowless) year - so whilst I can't comment on their snow performance, I've got a good feel for them year round.
In warm dry temps the grip is as good as premium branded summers I've driven on other cars, they feel progressive when pushing on, and I'm quite confident pushing them. Don't get me wrong - for a similarly priced summer I'm sure the performance would be greater, but if you're running them through summer the performance is solid. To summarise they feel like 'good,' summers rather than 'premium' winters when driving around in 25C+. Driving normally you don't notice that you're driving on winters. But I wouldn't run them year round unless you can avoid it - see below.
In warm/wet conditions they again do well and resist aquaplaning brilliantly - something the last summer has provided ample opportunity to confirm that.
In colder conditions they do what any good winter tire should - become very grippy. You can feel the traction increase as they temperatures drop and they they start to feel like a 'premium' tire. From 2C and below the change is very noticeable.
Noise and comfort are good and I haven't noticed any noise as another reviewer mentioned.
But if you're planning on running them year round - don't. Whilst grip and performance are more than adequate for summer use, wear has been pretty bad - I've got through a set of rears (down to about 3mm, so below the limit to be useful in snow) in less than a year/10,000 miles. They haven't always been driven conservatively, but that was a surprise.
But I've got a lot of confidence in the Sottozero 3's, so I've ordered a new pair for the rear and will be switching to dedicated summers when the temp increases. Great tire and hopefully I'll be able to update this with snow performance in a few months.