Really, i haven't had the opertunity to drive the Spark, just so few around...But looking at the numbers...
it is 3" shorter wheelbase and 2" narrower track, that should keep handling reasonably close to the feel of the Micra. The car is a lighter, so it could blow around a little more.
Really...I've haven't noticed anything in the Micra that makes it feel any different then most other cars...
I drive a Kia Van and a Motorcycle, both blow around far more then the Micra.