Not enough! I've had to use GRO NI to pay for some pre-1871 records in Down and Antrim (so far managing to correctly ID the records I wanted first!)
There are some transcribed already for some areas - for example I accessed some pre-1871 deaths in Clare on rootsireland.
It can be really useful to have the informant listed, sometimes unblocks some relationship quite far back on the tree. Even when it's who you expect, along with residence etc. it can really confirm you have the right record for the person you are researching. And of course we sometimes have so little information about these people that the cause of death can be of interest. Not a pre-1871, but for example, one such ancestor of mine it perhaps gives an indication of occupational hazard, for a "hackler" (i.e. flax comber or operating machinery for same) dying of long-standing bronchitis in his 50s.
Having the exact date of death also allows a match to grave inscriptions, or a trawl of the local death notices the next day or two, even when the newspapers are too poorly OCRed to hit on searches by name. At least GRO NI provides the date without needing to pay - plus you can filter by registration sub-district as well (e.g. Donaghadee, not just Newtownards). But for the rest of Ireland you need to hope you can get a transcription elsewhere.
