This is a age old question for investors, there is no right or wrong answer, it all depends on your circumstances.
Do you have more time than money or more money than time?? Do you like doing research or getting some else to do it?? What sort of returns are you happy to accept?
My view is that I like to remove as many people as possible between me and my investments. The reason is that the more people taking a small cut of your money the less left for you. Here's a worst case scenario;
Me -> Financial Planner -> Manage Fund Company -> Managers of Fund -> Tax Man-> Asset
All those people are earning some income from you. You can never remove the Tax man from it, but you can do things to reduce his cut.
I like to have ;
Me -----> Tax Man ----> Asset
Simply more returns for me, however this means I'm responsible for the total management of the asset. When I do have people working for me I make sure I get value from them. And I like to pay them direct so I'm aware of what they cost. Managed Funds and Financial Planners there costs are generally hidden from you or hard to fathom. I'm not against getting any help, far from it. Just that I like to know what I'm dealing with.
So are all managed funds bad, NO, however I prefer ETF's (Exchange Traded Funds) or LIC's (Listed Investment Companies) because of the much low fee's . I would never invest in a managed fund unless it could give me exposure I couldn't easily get.
As you may have guessed I'm a sort of hands on investor. I enjoy the process and I get hints and tips from all over the place. So I'm not just sitting in my office spinning ideas out of my head, 98% of the time I'm re-using some else ideas and thoughts, making them fit my needs. Only time will tell if I'm full of shit or there's something to what I think!