Generally very enjoyable to read a Frenchman's take on 18th century England. Two parts stood out:

The letters on Quakers were particularly interesting - there's something especially cool about reading an account of a rather normal interaction in the 18th century. It is easy to imagine Voltaire discussing the finer points of Christian theology over dinner. It's far too easy to think of past generations as fervent religious zealots, but Voltaire reminds us that indeed discourse did occur, even if it wasn't commonplace.

The letters discussing the current state of science and explaining recent scientific discoveries were just as interesting - Newton and Locke were in living memory, and Bacon not long out, so Voltaire provides a fascinating perspective on how they were perceived at the time (spoiler: it's not particularly different from how they're perceived in the present day)

I didn't find the letters on stage performances and poetry particularly gripping, though this may have more to do with my lack of knowledge/interest in these fields rather than the writings being of any lower quality than those described above. Nonetheless, it made the last quarter or so a bit of a slog, hence the three star rating.