Pros and Cons of Using Flex forms?

Hi,

We are considering using Flex Forms where users are entering account\entity combinations, to allow them to select particular account\entity and add them to their input form in Smartview, but have not used it before and are interested if there are any watch-outs or issues.

I understand that one watch-out is that users cannot drill up and down to make a selection (and may expect to be able to).

Are there any other watch-outs or issues associated with using Smartview Flexforms?

Many thanks