I think they can really be valuable if you're planning on travelling around a lot, but one thing i would say is try to plan out your trip so that you know where you want to be and for how long, because if you're not going to be travelling really often, then it might work out cheaper to buy single train tickets / coach tickets / bus tickets / even plane tickets eve, most of which you just pay for at the time, but some you can book in advance. A lot of it does depend on the countries, places like Italy, Switzerland etc have much more expensive travel than other places, so look into that. Also, do check out flight costs, because websites like ryanair and easyjet can sometimes have super surprising deals (my barcelona to london flight this June is costing 17.99GBP for example). But i've got friends who've done this, and it does seem the most economical way of seeing a lot of Europe in a short time. So if you wanna get around a lot it would be worthwile, but if you're planning on staying in a few places for longer periods I would look into local trains (I'm going to Slovenia and Croatia for a month in July and that's what i will be doing). Either way, have a great time, I always trip out thinking how big a commitment it is for Americans to travel to Europe, i'm sure you'll make the most of it dude.