Update 1/22/2018: Although Zoho is great in many ways, I have spent dozens of hours working around minor usability issues in Zoho Books (see a few examples below). I switched to Zoho Books from a similar platform mainly to save time, so I am reducing my 5-star rating to 3.
I did try contacting Zoho support about many of these issues, and the responses are usually along the lines of "sorry, we do not have that feature right now". Bugs get fixed quickly, but usability issues seem to be low priority for Zoho.
Original 5-star review from March 2017:
Zoho Books and Xero were the only invoicing services I found that had all the features I needed (import past invoices, online payment portal, recurring invoices, and invoice customization). After trying both of those, I decided that Zoho Books had much better customer support and was better suited for a small business.
Zoho Books has saved me tons of time. Some of my favorite time savers are:
* Customer statement makes it so easy to send customers an accounting summary of any time range. No more spreadsheet export!
* Customer portal and payment options are simply fantastic.
* Recurring invoices and automatic reminders save me time.
Also, they have great customer support. When a new release resulted in a bug that prevented me from attaching a text file to an invoice, a support rep told me a workaround for it, and the bug was fixed within a few days.
Of course, Zoho Books is far from perfect. The current version has some minor annoyances:
* cannot set a global bcc email (must add it to a bunch of places),
* no easy integration with mailing lists (to email all of your customers that purchase XYZ product),
* and transaction matching is so painful I no longer bother to do it.
But again, those are just annoyances and easy to work around. Zoho seems to be constantly releasing upgrades, and I would not be surprised if all of those issues get fixed soon.