TLDR; Not only is the new choice of font unfortunate at best -- the formatting reveals another level of amateurishness so very unbefitting to the ernestness one might assume the sender of the letter wanting to convey. ;)

Basic typography: a paragraph starts with indentation if there is no blank line of any height after the previous one. And if it is not the first paragraph. In short: indent or put vertical space. Never both.

The old TNR version gets this right: if you put blank lines between paragraphs, you don't indent.

Then the date -- dangling god-knows-where, aligned with nothing.

In the old version the only formatting faux-pas is the alignment of 'Sincerely' and if you're picky the outdent of the seal in the top left is a tad much (outside optical axis).