We went here for Evensong, which is an uplifting experience, and is an absolute must for anyone visiting Cambridge. On the night we went the Choral Evensong was sung by the choirs of King's and St John's colleges. The singing of hymns in such a beautiful setting is delightful, and highly recommended. On the downside, due to the popularity of these events you must get there early to get the best seats. We arrived half an hour before it began, and ended up a long way away from the choristers. You need to get there maybe an hour early to secure the best seats. Because the aisle is so long, you end up just staring at the people in the seats opposite, as the singers are down at the other end of the chapel. Be aware also that you are required to stand for long periods, and in some cases kneel if possible. And when you are allowed to sit down, the seats are jolly uncomfortable anyway!
