It is never a good idea to install a brand new release on a production system unless you have to (i.e. if it is the only easy way to fix a show-stopping usability/security/compatibility issue) - this goes for any software. Play safe and let the pioneers get scalped, and/or try it out on a less critical machine first.

I recently bought a new netbook and rather than waiting a couple of days or installing the beta to upgrade later I put an older release on. 10.04 in fact, rather than 10.10, as that is an LTS release and I was in a cautious mood.

For this reason, I rather conservatively remain with my LTS, no system crashes since the .1 release and I'm extremely happy with it, although I do miss the excitement of these new releases and its clear that there is a lot to look forward to in this release, especially if Unity is as good as some of the comments here suggest.

As a fellow day-job-using Ubuntu user, I'm with you. In fact, it's not just this release, I always wait a bit to upgrade, since the general consensus seems to be that fresh Ubuntu's are often a bit touchy :)

Not only are fresh Ubuntus a bit touchy, but upgrading in-place has bitten me badly in the past. It's always a clean-slate install for me now.

Apt is the only system I've ever felt fully comfortable with when doing upgrades. It was neither a problem under Debian nor Ubuntu.

Do you have a tendency to make system changes that get in the way of the upgrades? (i.e., where has it gotten stuck for you before?)

In the past I've found that if I installed packages that weren't in the main release I would sometimes run into gigantic dependency issues that I couldn't resolve without a clean reinstall.

I've never had a problem with a Debian in-place upgrade; I've got servers that have been upgraded from woody through to squeeze without a hitch. Where I've had problems with Ubuntu, it's been around the desktop, and udev/hotplug integration.

That being said, I've not given it a fair try for a few releases, so it's possible that in-place upgrades are better tested now, but I don't see the point of taking the risk. If it goes wrong, I'll end up reimaging anyway, so why waste the time?

I'm not the OP, but on my in-place upgrade to Natty today I had the nspluginwrapper installer die with a segfault. As a result, the update "failed" (only nspluginwrapper failed, really). I had to remove google-talkplugin to fix it (so really, the bug was in Google Talk, but apparently nobody at Canonical has Google Talk 64-bit installed to encounter this). So yes, seemingly-inconsequential system changes can interfere with upgrades.

Yea that too. I've heard bad things, but I've never even attempted it myself. Years of Windows has built up some serious negative reinforcement here :)

I have never NOT been bitten badly by an in-place upgrade

google-talkplugin is still broken on a virgin x86_64 squeeze.

It's no big deal if you don't mind having a few partitions on your system. Personally I have a large partition for my /home directory, and smaller partitions for testing out new releases, distributions and such. If one of the releases is/becomes unstable, you can just select your old reliable release in the boot loader and get work done on that. It has worked out really nicely for me.

The only issue would be if you run a newer version of a program that updates it's config file (or something similar) format, which ruins things when you boot back into an older partition running a prior version of the program.

This sounds like you do not have a working backup plan. Instead of installing the new Ubuntu, make sure you have a backup plan, test it and automate it to secure you against a random massive computer failure that would make you unable to get work done.

That's why I moved to ARCH a few years ago. Only once did an an arch upgrade caused problems; with ubuntu it was a pain almost everytime.

Arch tends to keep configuration formats and file locations between major versions. I've found that with Ubuntu, simple things like mouse button config change drastically between versions. I love Arch on the server but Ubuntu is just too easy and has so much software available for the desktop.

For the last few Ubuntu versions I start with Ubuntu Minimal (30MB instead of 690MB) to avoid all the extra noobuser bloat that comes with Ubuntu default. This way I have a clean installation similar to Arch but without having to hand-configure everything.

I'm going to run it in a VM for a while first

Agreed, although you can always try it out in a VM, on a spare partition or even a spare machine.

you can still enable the old desktop