The system is very easy to use, it's so simple that even my mother can understand how to fill up all fields correctly! It would be great if they offer some other payment systems such as PayPal for people who are not using credit cards.
I wish there was an option for me to send in invoices via email instead of having to log into their website everytime before sending one out. We have been able to create our own roadmaps with this software which has helped us allocate resources better than we could without it.