Extremist/nationalist parties are on the rise pretty much everywhere in Europe. Isn't it usually a good indicator that people are greatly unhappy? Granted that immigration may not be the only factor it is the favorite theme of nationalist groups.

Edit: I guess I'm being downvoted for not providing sources, my bad. http://www.nytimes.com/2015/06/20/world/europe/rise-of-far-r... http://wilsonquarterly.com/stories/what-explains-meteoric-ri... http://www.theguardian.com/commentisfree/2013/nov/15/far-rig...

I think it might be a good indicator that people are frightened, which is different.

Let's say unsatisfied then :) Either because they're unhappy or scared, in any case, they're not comfortable with the current immigration policies.