Just like any marketplace, it's not too difficult to get ripped off on ebay if you don't do your research beforehand. On the otherhand, I can list countless number of items that I got through on ebay that saved me tons of search time and/or cash.
And I don't see a big deal with sniping at all. I personally don't do it because it's a waste of my time. I just always bid the maximum amount that I'm actually willing to pay, and I'm done with it. Because of this, I can't think of a single time where I was outbid by a sniper on something that I really wanted. For those items where I didn't care too much and got outbid at the last moment, no big deal - the person was simply willing to pay more than me for it.