Yes, if anything they're more useful than ever. By not being able to see a score/like vs dislike total, or anything along those lines, your decision to up vote is completely uninfluenced, and 100% your own. That's very helpful in that it's unbiased. You might see a post with thousands of up votes and think "why bother" or "dang everyone likes thisbi should too". Without that subtle influence, you're purely up voting content that you felt was beneficial to you and others would appreciate.