Is 64 bit Ubuntu stable for general use?

Are there still general problems using the Ubuntu 64bit version ? I heard that most of the programs do not work out of the box?

Will I notice a significant speed-boost? Until now I have always used Ubuntu 32 bit.

I heard that most of the programms, does not work out of the box ?

No this is silly. Everything works for me — and has for many years — on more than one computer.

The two things that have been an issue in the past are Java (works completely fine now) and Flash (now has a native plugin and while that doesn't get as much love from Adobe as its 32bit version, still does the job just fine).

Will I notice a significant speed-boost ?

Significant? Probably not significant but notable. You'd get a much better speed improvement by say switching to an SSD or doing a general upgrade.

I'd still say if you've got less than 3GB of RAM (and you won't upgrade to 4 or more), stick with 32bit. 64bit does use more RAM so if you're already squeezed, that won't help.

If you do have 4 or more, this should be a no-brainer. 64bit works. There probably are some very insignificant issues but I don't think I've found anything that has actually stopped me.

All programs work well, right out of the box. Just like Oli said, if you have 3GB RAM or less, then stick to 32-bit. 64-bit uses more RAM, and if you have high RAM, say, 4GB or more, then 64-bit is the way to go.

As I said, all programs work well on 64-bit. The only program which has minor issues on 64-bit systems is Adobe Flash. Adobe only provides a 32-bit version of flash. You can run the 32-bit version of flash on 64-bit. It runs well, but a bit slower than on a native 32-bit system. A 64-bit version of Flash, called Flash 'Square' is currently in development. You can download it from here. I use Flash Square myself, and it works really well. Haven't noticed any issues yet.

I've not seen anything go wrong with 64bit since 10.10, but I still use 32bit on the desktop due to the amount of RAM I have (3GB). All of our servers are running Ubuntu Server 64bit with absolutely no problems.

I can vouch that on Server hardware and on Desktop hardware 64-bit has worked fine for me for ages.

32 Bit will use less memory than 64 bit. It depends on the application, but it is worth considering if you have a small memory system. Here are some 32 vs 64 bit comparisons:

http://kernel.ubuntu.com/~cking/x32/Quantal-x32-power-memory-comparisons.ods