Pros
Multinational company dealing with whole spectrum of Communication Service Providers allows to work in various technology areas (radio, core networks, systems integration). Roles related to direct customer projects (like in SI) give lot of opportunities of professional growth, when one seeks the responsibility. After some years of work may have a substantial portfolio of projects done for operators in various countries. On product side - range of innovative products in several Telco domains allow to work with cutting-edge technology. Direct (local) line management has good attitude to employees' 'daily matters' which supports work/life balance. Great team spirit on working level where engagement in order to deliver to commitment is clearly visible.
Cons
Becoming bit too unstable - lot of subsequent reorganizations don't give time to 'settle down' after a change. On has to like a hectic environment to enjoy working @NSN. Good plans for competence development are often killed by cost factors.