Just bought a Brompton today. That exact model. I'm a newb, so take what I say with the required salt, but here goes.
A couple months ago I got my first bike since high school/college days. I live in a moderately small apartment in NYC. After much back and forth, and web chats, I wound up with a dahon Jetstream. As a bike, love it. As a FOLDING bike? Not so much. Folding is pretty clumsy. Rolling is pretty annoying. Carrying is frustrating. You can't really drag it around a store, say if you wanted to pop in. so, you really have to lock it up. It starts felling less like a folding bike and more like a small regular bike. However, when you need to cram it into a corner at home, it works (although if I think I'll be riding it the next day, I don't fold it, so generally it would stay unfolded most of the time).
So, I just bought that dahon, and went out today and chucked out a bunch of cash on another folder. The Brompton's fold is *that* much nicer. The dahon feels like a nicer ride, but it has front/rear shocks and 20 inch wheels, so if it wasn't it would be a complete failure. However, Brompton has to be the best fold and roll/carry package out there, and for what I want to do, its worth it. For local city commuting, its perfect (ish).
Not sure about road trip, though. If you can fit it, and that's the bulk of what you want to do, the ride quality might be more of the deciding factor than the extreme fold. I plan on taking it on train/plane occasionally when I head out of town (train would be easier than plane, for sure).