I normally judge a steakhouse by the quality of the steak, which to be honest was only OK. That said I had such a nice time here that 4 stars doesn't seem to be fair either. 4.5 stars would be about right.
The location is truly amazing - there aren't many other places you can eat at with so much history. We felt a little odd asking our waiter about the place, but as the night went on most of the other tables asked about it as well. They have a little booklet that explains the history of the place which is worth asking for.
This is a great place for a romantic dinner. There are many elegant restaurants out there, but few that are housed in a legitimate, historic mansion. This location is the flagship of The Keg steakhouse chain and it's easy to see why.
Service was great as well. Our waiter was attentive without hovering and got us a free desert as well since we were celebrating our anniversary here. (This seems to be a policy here so definitely let them know if your celebrating a special event).
The only downside was the filet I ordered. There wasn't anything wrong with it but it wasn't amazing either (this is judged in comparison to the top steakhouses in NYC, which admittedly set a pretty high standard). My wife ordered a surf-and-turf combo with steak, lobster tail, and other seafood and enjoyed it quite a bit. The trio of small deserts we ordered were all excellent.
If all your interested in is the beef then you might be able to do better - but if your looking for the total package for a romantic dinner than this place is hard to beat.