Yeah, I used an agent once, for a honeymoon in Europe. She planned the first half but only booked a hotel for the second half and we did our own thing.
The first half was all tourist traps and places that were obviously giving a kickback to the booking agency. Oh, and of course double beds for our honeymoon. The second half was much better as we ran around London doing museums and attractions. It was cheaper too, despite being in one of the most expensive cities in the world instead of out in the countryside.
We have not used an agent since. Maybe if you could find a really good one it would be worth it, but such a person would probably be expensive.