The end user is fine - they are more likely to see results they are actually interested in. If a user doesn't trust a source and won't click on their links, they'll soon not have to bother scrolling past them.
The sites themselves actually benefit as well. Sure, they may be bumped from the first page of results for users that are unlikely to visit their site, anyway, but the tradeoff is that they get a higher position for the users who may actually visit their site. It's an ideal trade for those being filtered.
I suppose that leaves the idea that the end result is a "biased" internet. I don't buy it. Google is not removing sites that disagree with them, they are re-ordering them for different users. If your profile wasn't factored in, then what options do they have?
They could order on popularity, but biasing towards popular opinion isn't any better than biasing towards my opinion.
They could randomize the order, this would be without bias, but absolutely useless to anyone.
They could judge the objective truth of sites, but that's far more biased than any of the other options.