Kraken Pro is less intuitive to use, but the fees are much, much lower than the regular Kraken website. With crypto trades made via Kraken Pro, fees range from 0-0.4% compared with the instant buy/sell feature which seems to start at a 1% fee and can be much higher than that in my experience if using debit/credit cards.
The instant buy/sell feature seems quite predatory. It’s not at all obvious when you first make an account that there is another way to buy/sell crypto with much lower fees.
As far as I can tell, there are essentially no downsides to this approach. Despite the “Pro” name, no subscription or extra payment is required. The only consideration seems to be that you need to link a bank account.