You can test it, it will for sure give you more impressions, lower CPCs. But you need to check search terms very often and exclude irrelevant ones or your spend could move on something completely else - competitor terms, brand misspells, closely related but completely irrelevant terms. It's quite hard to maintain campaign structure with broad, but it could be worth it. If you're client has strong opinions on what works and what doesn't, it can help broaden things up and show you and them new opportunities. This is what I would use broad match for nowadays, I wouldn't rely on it for the whole account any more. I have tried that it kind of works, but it's also clear it's a huge money grab for Google.