Stayed here on a businnes trip in January and it was a nice experience. My room was on the 5th floor, facing Rosenkrantz gate, and there was no noise from that side. Relatively spacious room with all amenities I could ask for, and it was kept very clean. Good, free wifi.
The location is excellent, just a short walk away from the main train station.

The Grand is the "Old Lady" of Oslo hotels. It has a great reputation and bags of history. It is set in what is just about the best spot in town, a nice park on Karl Johan Gt (Oslos Main street) right opposite the parliment buildings and in sight of the Royal Palace. The main train station is a short walk up the street and with the fast train, you can leave your room and be in the airport in well under an hour.

The service was good, even at a busy time. I stayed December 31st - January 1st. (New Years eve 2011). The hotel itself appears to be very well presented, with huge paintings, mirrors, ect in the hallways, all very "Grand". The rooms are a little less grand. I was in a room on the Ladies floor (for some reason) and I would certainly have prefered not to be. The room was clean but the decor was odd. The only way I can really adequately decribe it is to say it seemed to have been decorated by a color-blind 4 year old with an Ikea obsession. I had booked a Superior double room and was less than impressed. On the other hand, positives for the room were an excellent bathroom and a very well stocked minibar.
I would also add to other reviewers comments here that I agree with. The Ladies floor is a fair old hike to the lifts. But it gives you plenty of time to appreciate the fancy corridors.

Can't really comment on any of the other hotel facilities as (surprisingly for me) EVERYTHING was closed in the hotel. Upstairs bar, closed. Downstairs bar, closed. Gym, closed. Pool, closed. Bar downstairs by the lobby? Open, but when I went in, they said no drinks!. There is no excuse for this from a top-class hotel. It was a big disappointment.

We had the New Years dinner in the Grand Cafe in the building, but apparently this is not part of the hotel so it would be unfair to comment on it here.

My overall rating for this hotel I think would probably have been a 3 had it not been for the fact that I consider what I paid for the room rate to be very good value (considering the prices of nearby alternatives). And I booked through the front desk too, no special deal, no cut-price website.

I wasn't entirely happy with my stay here, but I would probably give it another go next time I need an Oslo overnight stop.

I stayed at this hotel whilst on a business trip in January and must say my experience was not pleasant. No towels in my room the first night. My room was in the center near the ventilation units which were very loud and kept me awake. They also had several events over the weekend which involved bands so the music could be heard on the 4th floor. I should have know something was up when I received ear plugs in my room.

The room was nice and clean. Renowated bathroom.
I had a singel room with a queen sized bed.
There was some renovating work at the hotel, but it was told you by check-in and it was from 10 in the morning till 18 in the evening.
The service was very good, handed in some clothes and got them back the day after, nice and clean. I also had much stuff with me, and all was carried to my room, and from my room into the taxi.

A good old one, this is service like it shold be all over the world.