I have started using it just recently and I really like it. It allows you to schedule a listing for free (ebay its like $.15) so if I feel like ebaying at midnight but don't want my listing to end then, I can schedule it to start the next afternoon or whenever I want. It also lets you add more than just one picture without the extra fees. I have still been managing my auctions and everything in ebay, I'm not too fond of the way that Auctiva is set up for that. I just use it to list items and then never check it again.
Oh, the only problem that I have run into is that when someone purchasing something it takes them to Auctiva checkout and then to Paypal like normal. A couple of people who purchased multiple items had a problem getting the checkout system to accept the new adjusted total.