And it was fabulous! I would thoroughly recommend it if it comes to an Opera House near you. Although we were nearly thwarted by some different problems, first the lead female singer Joyce DiDonato fractured her leg on the first night! And so was performing in a wheelchair. Amazingly enough this worked really well, all things considered. Then at the beginning of the performance out came a lady and you could hear the collective groan of wondering what had happened. When it was announced the lead male singer had gone down with a cold so would not be singing but would still act and there would be a singer on the side of the stage! Again it worked really well, once you remembered to focus on the acting singer not the singing singer.
The Royal Opera House is also one of my favourite buildings in London. Inside and out. I took some pictures of the floral hall, now called the Paul Hamlyn Hall, which is just stunning. At the top of the picture above you can see the box where you can stand in the Amphitheatre Bar and look down on everyone drinking in the floral hall. 
I'd recommend to go just to see the building, and the operas are normally pretty spectacular too!