Platform is constantly evolving. For example, they recently introduced a future payroll module which would be a great tool. They are working on integrated payments and and invoicing, and a scheduling / workflow module. They are constantly updating and improving the platform.
Check printing. This has been problematic since the check printing template does not seem to work very well and we have spent a long time trying to get things lined up so that checks print correctly. Part of the problem maybe that this is an Australian company and the check printing capability is designed for Australian check stock. In any event, this appears to be a frequent complaint judging by comments on various forums I have seen.
Integrated payments (getting there). This is also an issue at the moment. It's not possible for our customers to simply click a button on an invoice to kick off making a payment. We are forced to work with a 3rd-party payment processor called Stripe, which adds another step to the process. This is not ideal since Stripe cannot handle recurring payments which is important to us. It would be better if there were an integration to the Authorize.net payment gateway since this is a better-known processor and can handle recurring payments. Xero is working on an integration to Authorize, and that will help a lot.
New revenue streams on subscriptions. When we were using QB, it was very difficult to set up clients on the platform. Since Xero is a SaaS solution we have a lot more options. For example, we can have clients subscribe and Xero bills us. We then pass that payment onto the client as part of their monthly accounting packages. Also as we are a Silver partner with Xero, we are featured on their website which generates more leads for us.