Having lived in Melbourne and San Francisco I am badly spoiled for Chinese restaurants. What you get in England tends to pale in comparison. There are some good places in London's Chinatown, but elsewhere a good Chinese restaurant is hard to find. Brighton, it seems, has one.
One thing that you should possibly not do, however, is go to a good Chinese restaurant with vegetarians. Not that I blame Tom and Antony for this. They liked the restaurant, and the Chinese make a lot of good vegetarian dishes. But it does mean that you can't have any of the set meals, which are by far the best way of getting to sample lots of dishes (and hence the quality of the restaurant) quickly. It means no crispy fried duck either, which is the one thing that Chinese restaurants in Britain do really well.
No complaints, however, I had a delicious prawn starter with a chili dip, followed by beef in black pepper sauce. It was good stuff. I've had better, but I would certainly be very happy to go back to this place. The boys seemed very happy with their food too. They are locals and I'm assuming that they would not have taken me there if they didn't like the food.
The décor is good too. Sun Bo Seng has a sparse, metallic look, without being threatening the way many such designs are. There was plenty of room inside. None of this cramming every diner in and not allowing them room to move. It is a nice place, and I liked it.