The functionality is just not very intuitive and kind of hard to use. I used to use Freeagent which wasn't perfect either but it was at least 2 stars better than the xero UI. I have worked in IT change including UAT of UI 's and had I been managing the testing of Xero I would have chucked it back over the fence to the developers. The search functionality in various screens is poor, a lot of the screens are very cluttered and as whole Xero has a very old fashioned feel. I have seen better software systems used to handle similarly complex scenarios as long as 15 years ago. I am fairly technically minded and have struggled with Xero, I imagine people with less of a technical mindset would likely be quite lost. Unfortunately when you are running a small business with limited resources it is not possible or practical to back out of an accounts system once you have started which is why I roll my eyes when I see the offer to "try for Xero for free", just another marketing hook.