The Ultimate Todoist Sync plugin enables seamless integration between Obsidian and Todoist, allowing tasks to be synchronized in both directions. Users can create, modify, or delete tasks within Obsidian, with changes reflected in Todoist. Features include priority setting, due date synchronization, and marking tasks as complete or incomplete. The plugin supports advanced customization such as file-specific default projects, tagging, and automatic synchronization at user-defined intervals. It also offers support for Todoist projects and priority levels through simple markdown syntax, enhancing task management across platforms.