Auction Defender is easy to learn, and very feature rich. It has all the usual functionality, including bid groups, multiple eBay IDs, time synchronization, international support... Some of the unique features I like are the advanced import - you can import auctions from any eBay search result, and the single-click adding of auctions from Internet Explorer - not having to copy/paste auction numbers makes life much easier compared to some of the other programs. When I compare snipe time with the actual bid history on the eBay site I'm usually within 1 second of the specified snipe time... Program is updated fast with eBay changes, I can't really think of any negatives, works great for me.