I think Wave is for the person that has a side business and wants to kick out invoices and accept credit cards.
Real accounting stuff like being able to take a receipt and split it between tax deductible stuff and personal stuff isn't possible with Wave. Another major issue is that there are no backups of your data - nor is it possible for you to make one. I had an invoice just go missing out of wave. Fortunately I had an email correspondence with a client about the invoice, so I knew the invoice date and the invoice number. Even with all that information Wave told me there was no way to get it back and they don't have backups of their system.
For the positive side of Wave, it's free, they allow you to take credit cards, and they have OCR for receipts, so all you have to do is confirm that Wave read it correctly and it will automatically find the date and total.