I think it can be hit-or-miss. Sometimes I feel like the Barneys brand clothes are still over-priced and that if you just stalk the Barneys store or Coop you can eventually get things for less money on sale. However I did get a black wool sweater at the outlet over two years ago and it's still in great shape even though I wear it all the time. The one thing that I love about the Barneys outlet is the accessories, especially handbags. I've gotten so many adorable bags there for under $30. Granted many of them aren't leather but they've held up really well.
Barneys stuff usually goes for cheap on ebay but obviously the selection is really limited so if it's not totally inconvenient and you really like Barneys brand then I think the trip could be worthwhile.
i actually was at one this past weekend after my apple-picking trip. they had lanvin bags and a botkier clyde. yes, the lanvin bags had broken clasps and the clyde was in the worst shade of green ever! but both bags were less than 30% of their original prices.
they also had some super cute barneys bags. lots were real leather this time and all under $50. they also have a lot of funky jewelry. they had tons of wendy mink necklaces for 1/2 price (still too trendy for me to pay $150)
as far as the clothes, i think that is where the selection is spottiest. sometimes i've gone there and bought cashemere sweaters for $29 and they have become staples in my winter wardrobe. it can also be a great place for jeans and shoes.
it's definitely my first stop when i go to the outlets, but i definitely don't go there expecting to find something. during a sale, i feel that regular barneys has decent to very good mark-downs (although sometimes those are missing at the warehouse sale! funny enough!).
I also think it could be hit or miss. There is an outlet like 15 minutes away from me, so I go maybe once a month to check their selection. I have gotten great stuff there though, like a beautiful cashmere cardigan for $90 marked down from $300. If it is far, I would just call them and ask if they could give you a general description of their current selection.
i've only really ever bought shoes at the barney's outlet, but they are always really great. i haven't found too many clothes--i agree with dot, i think that is their weakest area.