MrSlant - "do they still make harpsichords or is that a really old instrument that has been looked after really well?"
Yes, harpsichords are still being made but they are very expensive and also very fragile - both good reasons why I won't be getting one anytime soon and also because DH would kill me if he came home one day and found a huge harpsichord in the middle of the living room 
"The sound is much nicer than the one up thread."
Yes, I think so, too. There is huge variation between harpsichords, far more than the difference between pianos. Not just the sound but their keyboards also can be very different - some have tiny keys, like a toy piano. Others have nearly modern piano standards. This really gets on my nerves as I rely a lot of "finger memory" and it throws me to have to play on weird keyboards.
"How hard has it been to learn?"
If you already play the piano, it's easy to play badly
Coming from the piano, one tends to hammer down on harpsichord's keys, which doesn't work as they are quite light. And you also have to learn a bit of phrasing and ornaments, which are not as important in the piano.
I practice a lot at the piano at home, then practice on the harpsichord in the Conservatory when I can. It does transfer (sort of) but I have to play for about an hour on the harpsichord before my lesson, to get the most out of it.