I would say it was a neccessary step, like any other acquisition in business (Facebook purchased Instagram and many other startups). The only major difference is related to the status of Nokia, a former giant of telecom, but in a difficult period. Nokia`s management couldn`t accept some other buyer, since the company already developed gadgets for Microsoft, so it was the natural evolution
Personally, I consider that the Lumia series after the acquisition are more relaible