I use this facility regularly, and have done so since 1984. It has developed and improved a very great deal since I first used it, and beats most countries' corresponding service into a cocked hat in a distant corner.
It is well organised and makes the information quickly and easiy accessible. You pay £15 for a day and you get a desk with a computer terminal and a socket for a laptop and access to all the statutory records of births, marriages and deaths and the census. You can print out (at an additional charge) birth certificates more than 110 years old, marriage certificates more than 75 years old, death certificates more than 50 years old, and census records, or you can just transcribe them. If you are struggling with the system, or having trouble deciphering something, the staff are very helpful.
Incidentally SunTanScott who complained in his review about being ripped off was factually incorrect. Contrary to what he claimed, you cannot view births less than 100 years ago on either of the Irish sites he mentioned. For online access to the GRONI site he mentioned the cost per certificate is £2, and you cannot save or print it, and it expires after a few weeks, while the cost of the corresponding certificate from Scotland's People online is £1.50, and you can save it or print it and view it indefinitely. You only have to pay the (admittedly hefty) fee for a certificate from Scotland's People if you choose to get a certificate of an event more recent than the cut-off dates. If you are in a Scotland's People Centre there is no additional charge if you transcribe the information in-house, even after the cut-off dates.
There is an in-house cafe with a modest menu, and there are changing exhibitions in the main bulding which are free of charge. The building itself warrants a visit just to see the inside of the dome, and of the Historical Search Room upstairs.