In no particular order:
1. I bought the all-steel version (from a dealer who had it in stock), partly because this was what I could afford at the moment, partly because a titanium S2 didn't seem to be in stock anywhere, and partly because past test rides had led me to think the titanium version too flexy. I now wish I had the titanium version, because I find the all-steel version a bit too rough of a ride. So, on the titanium-or-no-titanium question for potential Brompton buyers, I come down in favor of it, to my surprise, because of the flex.
2. The EZ wheels seem to me to be useless. The bike won't roll at all. Perhaps this is because my rear fender arrived (via UPS) a bit misshapen. I had never ridden a Brompton with the EZ wheels before. My heels are banging against them a lot whenever I first mount the bike and begin pedaling, and then for some reason, without my consciously trying to avoid it, this stops happening as the ride continues.
3. The raw lacquer color (or non-color) was apparently suspended because of "inconsistencies." My bike seems to have one, and as silly it may seem to care about this when the finish is supposed to look rather rough anyway, it bothers me. Basically, I have a "nick" on one side of the main tube. It's the color of the bike at the welded points, and the nicked area feels rather raised. There is also a kind of slick trail all along the tube, as if something scraped/rubbed against it? I'm not sure if the "nick" is a Brompton inconsistency, or a sign of the bike having been--nicked. While I'm not thrilled about this, I have seen much worse scratches on new, full-priced bikes on dealers' floors lately.
4. It's too heavy to carry without walking in a ridiculous posture. I'm 6 feet tall, 165 pounds, in very good shape. I make all of my weekend trips wearing a 46 liter backpack which doesn't tax me at all. But I can't walk uncrookedly while carrying the Brompton.
5. The stock saddle sucks. The dealer didn't have a Brooks on hand in the color I wanted. I think I'm going to go for the dark green... I forget the name of it. Sub-$200.
6. The highest gear on a 2-speed Brompton is high enough, even if you're a serious gear pusher. I learned this, to my surprise, on a recent test ride. The Brompton simply loses momentum too quickly for you to have any opportunity to capitalize on that momentum by switching into a gear in the 80's/90's in terms of gear inches.
7. As I said, my rear fender is way out of whack. It's in contact with the wheel and I can't personally see how to undo this. There are no Brompton dealers anywhere near me.
In general, I'm feeling a bit of buyer's remorse. The LX/XT Birdy would have been lighter and, I now think, wouldn't have been that much larger, in its folded state, than the Brompton. Lugging this thing about today, I no longer feel like the Brompton is significantly smaller than its closest competitors. I could have had that Birdy for the same price, bought directly from Pacific Cycles... Hm.