I followed the step-by-step instructions in the BOI LTR website. I submitted all the required documents. A few they came back wanting additional dicumentation, or a different format, but always specific as to what they wanted. I was confused on a couple issues, both times i emailed asking for clarification. In both instances they replied promptly explaining clearly what i needed to do. Took about 2 months from my initial submittal to being approved. I then booked my appointment to pick up my visa in Bangkok. Not that bad of a process.