I found that it was accurate if my BG was between 5 and 8. If I was higher than this the readings were often way out and add I relied on them I would have massively over-corrected. BG of 9 sometimes gave be readings of 17! When I was in the low 4’s I would get readings below 3, and it wasn’t because my body had reacted to a hypo and the Libre was 15 mins behind - I was doing BG every 15 mins just to test it so I knew that no hypo had occurred.
As another poster has said, it is great to spot trends. I went to bed at 5 and woke up at 5 but what I hadn’t realised before the Libre was that I was rising in the early part of the night and then falling back before I woke (over-compensating for the dawn phenomenon).
If you are self funding, it may be worth looking at the Dexcom G6, which has recently launched, and is believed to be much more accurate. If you search for it, the launch can be viewed on You Tube. Based on their prices it is slightly more expensive but forums say that the transmitter lasts much longer than advertised so the cost is less as they are replaced less frequently.