I didn't really like this guide very much.
The maps it contains are a completly mess, you never know where to look for the places it recommends, mainly beacause the places of interest are not marked on the maps, only bars and restaurants.
However, the information it provides is good enough for a few days in Helsinki. Good information also about nearby places to visit.
Didn't really try any of the accommodation or restaurants it recommends, so I cannot tell if they are good.
The size is fine to put it on a pocket!