Difficult, this is the word spoken by many SEO professionals after Google's sudden changes. Actual definition of this difficulty is that Google is concentrating on Quality not Quantity. So if you are doing quality work, no need to fear from any search engine, just do your work and you will get reward soon. I am in this field from 6+ years and always believe on the above mentioned things. That is why me, individually as well as in my company delivering RESULTS.