By all weather tyres i presume you mean something like a Michelin Cross Climate+ rather than an actual full winter tyre?
The Cross Climate+'s are very good as far as the reviews go, but they won't perform as well as a full winter tyre in the harshest wintry conditions. Nor will they perform as well as a true summer tyre in hot weather. They will however outperform summer tyres in winter, and winter tyres in summer.