Shakespeare first said it, and it still holds true. Last night I was watching The Apprentice and wanted to jump through the TV screen. One of the contestants was creating a brochure that was a novel.
Of course, Donald Trump hated it - it was too long, too wordy. When creating any kind of marketing material or sales letter - the shorter the better. People don't like to read a lot - so they won't. You have to get your point across in short, capturing sentences.
Try bullet points. Of course, the key to brevity is being able to get your point across in few words. So, you must really know what you want to say. People care about benefits - they want to know why it matters to them.
Keep it short and to the point - the benefit to the prospect or client. Try writing it in a fashion that grabs their attention. More people will read it and respond.