I stayed there for a month in July as part of the Guildhall School of Music and Drama's summer school program. The rooms are very spacious and generous as they are dorm rooms during the year.
The type of apartment I stayed in was in the newer addition of Sundial Court, so all the fixtures were newer than the original court area. I can't comment on the rooms in the original building because I never went over to them. In the newer side, where the front desk entrance is - the apartments generally have four or five rooms each, two bathrooms with standing shower stalls, and a kitchen with dining area. Each room has a bed, wardrobe, dresser, desk, chair, and sink with mirror. The beds are comfortable and the cleaning crew during the summer are very fast, friendly, and efficient. The only issue I noticed was that the elevator was slow and temperamental. It might be fixed by now, but it was always easier to just walk down the stairs than wait for the elevator.
It's pretty conveniently located and a short walk away to either Barbican Station or Liverpool Street Station. I recommend that if you're arriving, you should go to Liverpool Street Station since walking on the road underneath the Barbican facilities can be quite intimidating. Also, there are stairs at Barbican Station - whilst there are escalators at LSS. If you're coming from Stanstead Airport on the train, you can walk off the Express and cross over a few blocks easily to Sundial Court.
There are two pubs facing Sundial Court, but the establishments in the area get most of their business during the week from the workers in the office buildings, so the area can be rather dead on weekends. A Waitrose Supermarket is just around the corner (behind Sundial Court) so that's a good place to buy food to eat (as well as bottles of cheap vodka).
Note: There was no internet access when I stayed there last year. If you were lucky, your room faced the road and you could pay for The Cloud's City of London Wifi coverage. Otherwise, you could either wander around Barbican Centre until you could steal from someone's unprotected signal or go to the Barbican Library to use their computers.
You can find pictures of the rooms at http://www.gsmd.ac.uk/school/student_facilities/accommodation/sundial_court.html
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC