Finmei has a long way to go, BUT it does seem like they are on the right track. They allow multiple currencies, brands, languages all under one account. That is a huge plus.
Also it feels like they will add to this and improve it. They are listening to input.
There are many small things that need to be added. For example, duplicate invoice would be nice, when you have another invoice to do that is very similar to a previous one.
I'd like to be able to choose an invoice country and then design an invoice that is highly suitable for that country. For example in France you need to include the date when the work was delivered. You don't need that in the UK. So rather than have to type it into the notes field it would be good to internationalise invoice requirements.
It would be good to be able to add our own labels too for fields. For example in Europe you only need to specify the bank's IBAN, but in the UK you need an account number, sort code and account name.
Hopefully these things, and others will come in time. However, right now it is 100% useable and I am using it for my invoices right now.