I love Hillside for breakfast and come whenever I can.
The meat they use is of a very high quality, and makes everything amazing. The Levain bread is really fantastic. Basically everything food related is great.
The problem, as many have noted, is in Hillside's service. I've had a number of servers who have been very good, so it's not a systemic issue.
But, that being said, there are a number of servers who are about as bad as it gets. They won't come to take your order until you've been there almost 15 minutes. They drop the food off and you'll never see them again unless you flag them down and almost yell to them. These folks aren't unfriendly, but they're also not exactly caring about your experience.
So, you're left with the feelings that I have: hope that Yelp gets the management weeds out the poor servers, so this place can be the 5 stars it should be.