On top of the other points raised here, it's worth noting that LetsEncrypt is relatively new and until recently had another company higher in the signing chain so that they could provide their certificates without folk having issues with their local cert store.
On top of the other points raised here, it's worth noting that LetsEncrypt is relatively new and until recently had another company higher in the signing chain so that they could provide their certificates without folk having issues with their local cert store.