When I saw the Xtracycle on line two years ago, I emailed a friend that I'd seen something that was, fortunately, too pricey to be tempting. My first impression from their website was that it was something for Californians with too much discretionary income to purchase and feel green with.

I spent more time on the website, and asked my bike shop guy about 'em and he said he'd be glad to put one togehter for me. I had a few emails with Laughter Medicine. I took a deep breath on a Friday at 2:00 CA time, January 6, and called 'em... and got a priceless answering machine message telling me they were like, taking a few days off at the end of the year and I could reach Kipchoge at x number, somebody else at y number, and I could reach Laughter telepathically.

I gathered my siblings 'round after 'business hours' so they could hear the message... but a live person answered
then

I got one of the things and had it put on my Giant Nutra hybrid. Waited for buyer's remorse.

There are now a dozen of the things in this college town. At least for *me* with my often painful incompetence dealing in things like how to pack things on bikes (if there's a way to put something on backwards and/or upside down, I will do both), this thing is completely awesome. I can bring everything in the world with me everywhere. It's like having the back seat of a car on the bike.

Oh, and it's a great place to mount a Christmas tree...

... and it also announces with its very presence that this is a bicycle somebody bought on purpose - not because they were waiting to afford a car, but because they wanted a good vehicle for getting around and doing things.

I can't really speak to locking issues - I lock it up as I would my bike, but where I park thigns haven't been swiped. I find it handles very easily and the long wheel base and the drum Y& disc brakes make this utter weenie really happy riding in sloppy conditions. I've taken it up 15% grade hills on occasion, but 'round here overpasses are the main grade challenge.
It was something very different from anythign I"ve experienced with a bicycle... so speculation about it with regular bikes as a reference is of limited value. Ya gotta ride one... and even then, it's only 'til I lived with one that I really got to know its nature. WHen I started waking up and hearing horrible weather reports and the bike said "that's okay, we can go!" ... welp, I sold my car last May just because my brother needed it and I haven't missed it. (I have a few other steeds in the stable, too.)