HTML layout very bad, neat little bullet points bad, good copy bad, lack of line spacing and excessive terseness good.
Don't waste time on presentation, so you don't feel like a marketroid.
What I'm saying is that the more personal-seeming it appears, the more attention the reader is likely to pay. An actual handwritten letter presents as a highly personal communication. Even where it's justa courtesy note, it says that the other person values your business enough to take time to literally put pen to paper. For example, a few times I've bough a used book via Amazon and it arrived with a hand-written note of the 'thank you, hope you enjoy it' variety. It may be done by some junior employee, but any firm that does that goes straight into my 'preferred sellers' list because it's a rare flourish of personal courtesy in a world where most things are mass produced and commoditized.