Look at a feature of allowing auto import into zoho books through other conventional accounting softwares. Most companies are on ERPs or other traditional softwares but which supplement their core manufacturing or service activities. It is not practically easy to change those softwares. Allow an option wherein data from those softwares can be imported through FTP or even an auto email with attachment. An API cannot be used or integration method will also fail as in most cases these software companies do not want users to shift from their softwares to Zoho. Zoho Books is a good product but unless there isn't a seamless integration, many people wont be able to use it.