Revolut is a good choice for investors that want to buy and sell major shares and cryptocurrencies. No funds, or smaller cap stocks, but a good entry-level account for most investors.
One of the most commonly asked questions about new banks and fintech is if they are a safe place to keep your money. The answer is generally, yes, if they are regulated by the FCA as funds are protected by the FSCS up to £85,000. But, Revolut, is regulated as an e-money institution and not as a bank so you do not get the FSCS protection.
Revolut says that if they were to go bust, client funds would be paid out of a "safeguarding" account which is a type of ringfenced account where client funds are held. When funds are in this type of account, Revolut cannot (in theory, at least) lend them out or use them to run the business. This is how banks traditionally made money, they pay you a smaller amount of interest than they receive on the money they lend out and make a profit from the difference (among other things).
For small money transfers, Revolut is safe enough, but as with all currency conversions if you are sending over £10,000 abroad you should be using a currency broker. You'll get much better rates, more control over when you buy and sell, help with all the AML (anti-money laundering) issues that may come up, and the ability to lock in the currency exchange rate for up to a year in advance (if you think it will move against you).