I found the Libre very inaccurate as a replacement for finger pricks: a single sensor over a two week period was sometimes within 0.5mmol/l compared to finger pricks and sometimes 2.5mmol/l difference. It was closer within a normal range of 4.0to 7.0 but further out when high or low.
However, the direction and timing was close enough to understand which foods and activities caused rises and lows.
So, if you are planning to use it instead of pricking your finger you are not using it to its best. If you use it to time and quantify your insulin doses, it is very good.