I don't know if this will help with your potential ulcers, but here goes.
We got global passes in 2009 primarily for the convenience. We did have to make special reservations and pay extra for some trips, but for the most part it was convenient. However, it was definitely much more expensive than p-t-p would have been, and I won't get a pass in the future.
This is roughly the parts of the routes we took where the pass was used: Frankfurt, Koblenz, Munich, (Nuremberg), Munich, (Dachau), Munich, Venice, Rome, Catania, Salerno, Genoa, Antibes, (Nice), Antibes, Carcassonne, Barcelona, Madrid, Seville, (Cordoba), Seville, San Sebastian, Sarlat, Bayeux, Paris. The towns in (parentheses) were side trips from where we stayed.
The passes worked for a boat from Bingen to Koblenz. I think we got a discount for the Eurostar to England. We used lots of other kinds of transportation including buses and rental cars.
I'm not sure what you mean about "horror" stories. Pass or not, getting from one place to another by train is a challenge when you haven't done it before. The only other time I ever had a pass was in the late 70's when it was easy. You just got on and got off with the pass. Now there are probably millions of trips being taken on the trains each year, there are tons more people taking those trips and there are probably hundreds more train options than way back when.
Depending on your route, you may be able to just hop on and off. Or you may have to make reservations and pay more money. It's hard to say without knowing what your itinerary is.
If you have an idea of your potential routes, use the DB Bahn website (http://reiseauskunft.bahn.de/bin/query.exe/en) to scope them out -- even for countries other than Germany. My favorite part is being able to click on a map that shows the actual route.
The Man in Seat 61 has helpful information for pass users -- http://www.seat61.com/Railpass-and-Eurail-pass-guide.htm. That information may allay some of your fears.
Now, about that "uneventful trip" part. I'm not sure what you mean by that either. "Events" can happen that are beyond your control and there is absolutely nothing you can do about them. You just have to go with the flow. Some personal examples from 2009 -- mudslide north of Catania delayed the train for 2 hours while they cleared it; train going from France to Barcelona stopped twice and passports checked resulting in someone in our car being put off the train; train stopped in a small town several km from Sarlat due to some kind of track problem resulting in a 3 hour wait, a lovely meal at the bistro across the street from the station and a fun bus ride (provided by SCNF) on to Sarlat. All of these events had effects on what came after, making us late. None of them had anything to do with the passes.