I was staying down the road from the Carlsbad Outlets and decided to stop in to Ruby's for some burgers. The diner is within the outlet strip mall but is still decorated in Ruby's 50's style, complete with a model train running up above the diner's heads.
I ordered an aloha burger, my wife ordered a turkey sandwich. The food was okay. Nothing terrible, nothing spectacular. Prices were what I would consider the norm. The place was moderately busy but our service was fast and the waitress came back often to refill drinks and check on us. The milkshakes were great, and came with the mixing cup so you get a good amount of milkshake with each order. We tried peanut butter cup and strawberry. (We later went to the Ruby's in Oceanside and also tried the Black Forest. All were good, but we both felt the strawberry was easily our favorite.)
Overall, this was a pretty good diner experience. After eating breakfast at the other Ruby's, I will say that I think the food quality for their breakfast is better than their dinner.
One tip: Join the Ruby's eclub before heading out. They send all sorts of promotional offers, with the first one being a free milkshake. Definitely worth the couple of minutes it takes to sign up.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.