The author of the letter is leaving their current vendor, referred to as "Larry", due to various issues such as slow reaction times, inflexibility, and inability to support mixed workloads and data types. The author finds that other vendors, specifically those in the NewSQL crowd, offer better performance, scale, and flexibility at a lower cost. The letter expresses gratitude for Larry's efforts but states that it's time to move on to a more modern and forward-thinking vendor.