I went into a store to buy Vista 64 and the salesperson/manager refused to sell it to me since it was buggy and crap (his words)!! This surprised me, since it was advertised on their website!!
My experience is that salespeople/managers are not exactly knowledgeable about what they are selling, though they like to pretend they are. Vista 64 is not particularly buggy, at least in my experience. There ARE: (1) driver issues, (2) an additional layer of software incompatibility issues over and above those encountered with Vista 32, and (3) an irritating inability to install unsigned drivers, leaving you unable to run some 64-bit programs that worked with WinXP 64. These might be perceived as "bugs" by a salesperson but in actuality, they are not. They DO make it more difficult to move to Vista 64 when compared to Vista 32.
In my case, I have relatively new hardware and I was able to find Vista 64 drivers or XP 64 drivers that worked. Some of the first generation Vista 64 drivers do not have the functionality of their XP counterparts. Some of the drivers are beta with the attendant possibility of bugs. The only piece of hardware I could not find drivers for was my Adaptec 2940U2W SCSI card, which is hardly a new piece of equipment (i.e. from 1998). So I went on Ebay, picked up an Adaptec 29160 Ultra 160 for $25.00 and my SCSI drives were back on-line.
Once the drivers were installed, Vista 64 proved to be very stable and basically ran flawlessly. Bottom-line: thoroughly investigate the driver support for your hardware before choosing Vista 64. The driver support is kind of spotty even with new, top-of-the-line hardware.
As for software incompatibility, I had to:
(1) buy AVG professional since AVG Free won't work on Vista 64,
(2) give up ATI Tools and mod my Video card BIOS for fan control,
(3) buy Nero Ultimate because Nero Lite would not work,
(4) run Norton Ghost 10 from my WinXP maintenance partition since it would not work on Vista 32/64 and Norton is not about to release a patch,
(5) run Norton Partition Magic from my WinXP partition for the same reasons,
(6) have a massive struggle with my IPAQ 2210 and the windows mobile syncing software (which was fixed by wiping my handheld and upgrading the ROM with a newer version of Windows Mobile), and
(7) find replacements or do without some of the little utilities I've come to rely on.
Bottom Line: upgrading to Vista 64 is not for the faint of heart. It might take a couple of weekends to get everything working and tweaked to your satisfaction. And if your hardware does not have 64 bit drivers, you're SOL (and don't forget drivers for your printer, scanner, keyboard, mouse, joystick, NIC and sound card!). But, Vista 64 is NOT particularly buggy...