Google and digital marketing

Everybody is talking about using Google to drive up the page visits and thus drive up the conversion rate for the sales. What is the place of my website on Google? Shall I buy the ad word? What are the keywords that my customers are searching?

So many start-ups or median search engine optimization companies

So many guesses around the algorithm of how Google rank the page

So much money fall into the pockets of the "social media marketing" company and Google

But

Is Google marketing really so effective?

Of course I can not google it: suspect google not place the article question the effective of google itself too early.

My feeling is that when everybody is trying to rank high in google, the direct high rank of the commercial website is not effective- ie. conversion rate. But the microsites are more effective to transfer no. of visits into the conversion rate. Since customers have already read about the product from a third party in a non sales driven way, the credibility is higher.

What do you think ?