DO NOT USE FOR BUSINESS ACCOUNTS.
I have had a really positive experience with personal accounts, so I decided to try a business account.

The business account is a business account by name only, it lacks basic features that are needed by many businesses, even self-employed sole traders. (Especially if you plan on growing your business beyond making pennies). 

Firstly, you can't have an account in a business name, it must be in your own name. They say that the reason is because their business account for sole-traders but even sole traders have registered business names—which are often better used on accounts for tax and business purposes. 

For example, to sell on Amazon, they are more likely to accept an account in your business name. They will outright not accept N26 as a business account, not even for personal proof of address. 

N26 do not have any process to get a Creditor ID for direct debits or SEPA transfers - often a basic requirement for a business in Europe. They "Do not offer this feature". A Creditor ID is not a "feature", its a financial process to register your business to instill trust in customers. 

They block large transfers. Because their support is never spoken, always with random people, getting real support is hard.

It's impossible to have a personal and business account at the same time, removing the ease of dealing with the same bank for all your needs. I also think this highlights the fact that their "business" account is not a business account at all, but actually a personal account with slightly different T&Cs.

Personal account - 5 stars
Business account - 0 stars as it's not a real business account. Calling it that is just an advertising ploy.

EDIT RESPONSE TO N26:
Freelancers and the self-employed  working under their own names often STILL have customer-facing business names. Having one doesn't exclude the other.

The inability to use an N26 account EVEN for personal verification processes highlights a serious issue with calling it a "business account". It was refused by Amazon, a local bank and a payment site for personal address verification—not business address verification, which would be even more rigorous. 

Also noted the lack of response to issues like blocking transfers or no Creditor Ids given (which can be given to sole traders working under their own names by every physical bank I know).