I have a seasonal/holiday lighting business and my installers were struggling using the app, not sure when to close out an estimate if it did not sell (even after going through tutorials and training)... I received many comments on its 'clunkiness'.
As a business owner, I was surprised it did not have an API that I could use to integrate with other apps (which is a common standard these days). I also had no way of tracking online conversions into Google Analytics (we use their landing page that has their form for self-booked appointments, but no way to trigger a conversion in GA - when I asked Support about simple conversion tracking it was like I was speaking Greek).
We also had an issue where the admin email address could not be an alias (e.g. firstname.lastname@example.org) as their server saw this as a bad thing and would refuse to send us email to that address...When I asked, I was told they have 99% deliverability and that it is on our side. This forced me to use a single mailbox as an admin email in order to receive their email notifications...
When I tried to export to a CSV, instead of providing me the CSV instantly, I had to wait for them to send me an email (which seemed odd as the file is so small... the email notification did not work one weekend due to what I mentioned above, and their after hours support team was clueless, so that delayed my operations during a peak time for me).