It's easy enough for anyone in our firm who has not used it before to use with little training required (it comes loaded out-of-the box).
I have no complaints about this product at all - we've been using archadmin since 2013 without any problems whatsoever! We're solving many different administrative tasks that were previously handled manually so there isn't much room for improvement here. If someone was considering another package because they didn't like how things are set up in their current one then I would highly recommend giving this system a try first as everything can be changed if needed afterwards via simple admin controls. Having access to invoices for clients allows us to keep track of costs more easily than doing them through paper files and also makes filing expense reports easier when submitting reimbursements from client accounts faster.