My only issues with TransferWise have been having to ask recipients for their full addresses and then manually having to translate address schemes into something that fits in the boxes TransferWise provides in their forms. Sometimes things don't map over 1-to-1 (some Japanese and Taiwanese addresses, for example). I've also found that some Japanese banks only have one branch without a name and Transferwise requires a branch name. I eventually figured things out by researching the branch number online though.
All minor gripes though. Transferwise has let my business operate smoothly and make connections to vendors that would otherwise be cost-prohibitive to pay.
OTOH, I'm in Canada, and I've only used them for personal transfers. I have no idea how they perform for businesses, nor do I know whether they work well for individuals in other countries.
We've moved hundreds of thousands of dollars through them over the last couple of years with no problems on their end (we've had problems with banks failing to transfer correctly though..)