We tried it in Alaska and thought the food and service were very good. Steak was served as ordered and was a better cut of meat than the steak "always available" in the dining room. We are not happy about alternative dining venues that charge an extra fee - but we did feel this one was worth it.
We were not impressed with it on the Ocean Princess, but I believe it was probably an 'off day' - it was brand new, JUST opened, and I think they still had to iron out some of the wrinkles. As juliejoe says the steaks are all 'prime' (and large). I too would not normally use alternative dining (Scottish heritage...lol) but we were with a group. If you really love steak, try it.
One of my clients just returned from Sea Princess during there 7 day Alaska cruise she told me they dined in the Steakhouse 3 times. Really enjoyed the food. They loved the fact it was not as busy as the Dining room.