eurail pass: big help or big hassle?

I am going to Europe for the first time this summer, doing a contiki tour (Amsterdam to Barcelona) and then backpacking around a bit afterwards. I have been hearing really conflicting advice regarding whether or not to buy a eurail pass, so I was hoping that anyone here with experience travelling to or around the specific places I'm planning to visit might be able to offer tips.
    I would like to go from Barcelona to San Sebastian, and then on to Bordeaux and Lyon in France. From there, I'd like to visit Italy and travel to Venice, Florence, Naples (and Pompeii), and Rome. 
    I am hearing that in France and Italy (though I recently read Italy and Spain) you HAVE to make reservations for any train trips and that these are a considerable added expense if you're planning to do many of them. I cannot find any available schedules or fares for the time of year I'm going (September), but in some resources, point-to-point looks like it might end up being cheaper. Yet everyone tells me I should get the pass! 
    Has anyone done any of the legs of the journey I'm talking about? What's your experience travelling with (or without) a pass in France, Italy, Spain, and across their borders?
Would really appreciate any advise as I am very broke and don't want to end up spending money that I will regret....
Thanks! jaxx