Just like anything else, Sandra, it is all about what you make of it.
If you have auctions running consistently (you don't have to have 40,000 - but ALWAYS have something running), and you stock your shop with not just the majority of stuff being "what you tried to auction 3 times and it didn't sell" but items that are add ons to what you have at auction you might see some results. (auction off the evening gown, and then use the crossmarketing tool to show that you have 2 pairs of shoes in different sizes that would match perfectly and an evening bag to go with it that might not stand on its own with the dearth of things that are on ebay - but if someone is shopping with you already, the lure of combined shipping might make them spring).
The ebay store works best all around you have modern items where you have multiples of them to buy right away in your ebay store and the auction is just a way to advertise that you have them. But what it also offers for folks is some different crossmarketing tools, etc. If you have inkfrog, etc you can use their gallery set up instead, but its good to know about.
But on the other hand, if you put no promoting into your ebay store, you will only have sporadic success. Just like anything else, I found that when i went out and publicized my ebay store, sell through rate was much higher and so was ending price. Its not something where you can just list and hope for the best if you want the best results. There are people here who have great success at ebay stores, but those folks would be a great success at any venue they chose.
The listing fee on store items on ebay is super cheap - its the FVF on auctions, etc that are skyrocketing.
I have found more and more as time goes by on having my mall store that the biggest hurdle is promoting two different messages. "come to my mall shop" but "come to my ebay store". When i really want them to come to my mall store, why promote both?
Now I am pushing my website (excuse the dust - still not 100% done yet..will be at the end of the month!) and from there i can direct people to where i am. I changed the look of my mall pages so it looks like you are still on my site when you click there, and i can choose to direct people to my auctions if i have them, but this way they are no longer counting on me to list what i have in the mall cheaper on ebay if only they wait. Mainly i find that i just use auctions for clearance, and oddball stuff but mostly only participate in group marketing like VTA.
I am a little leery about closing my ebay store. I don't have much in it, but i promoted the url to my ebay store for several years and because my ebay id is different from my shop name, for the people who still are typing the store web address in, will they no longer find me. Its a little baseless because i keep in touch with my newsletter, but some customers from aw hile back have not subscribed.