Yes, this place is VERY overpriced, however, it does have some great gourmet foods, and unique fruits and vegetables when you're in need of those and can't find them in the supermarket. (Think Meyers lemons, okra, anise, etc.)
I would not use Eli's for an every day shop, but when you're cooking a special meal and need some hard-to-find ingredients, it is really handy.
The cheese selection is some of the best around. The bread selection is also fantastic, and they'll slice it for you upon request.
They have a great French dairy section with real French butters, and creme fraiche. And, once a year or so, I indulge in the clotted cream which is excellent, even if sinful!
Considering the price of things, I can't say the staff is as friendly as I'd hope, but hey, you can't have everything.