I see no reason not to upgrade when it becomes available. Metro isn't nearly as bad as the crybabies would have you believe. It's just a new way of doing things, and people tend to have irrationally defensive responses to change.
Win8 for desktops: upgrade for an improved Start menu. Not much of a reason.
Win8 for portables: perfect input device.
I'm holding off for Win 8 for the following reasons:
I hate laptop trackpads except for the MacBook trackpad
I like the MacBook multi-touch interface, but it is too small
Vista is still fresh in memories and expectation is another Vista
Microsoft remembers Vista and will throw money at early adopters hardware manufacturers
Hardware manufacturers will compete for Microsoft subsidies
The Win 8 multitouch implementation is perfect for portables
If you use a Win 8 laptop, you will wonder why it took 30 years to get here. It feels natural. Having multitouch on the screen is an obvious solution unless you have peanut butter on your fingers. But screen cleaning technology exists and: do you really type with greasy fingers?
Take a simple operation like dragging a window. Move hand from keyboard to mouse or track pad, move pointer to title bar, press button and hold down as you drag to target location. Contrast with lifting index finger from the keyboard to the laptop screen, pressing and dragging.
Hardware manufacturers are holding off Win 8 optimized hardware until around September. Expect cheap 13" multi-touch laptops with 1366x768 or better displays. Do not expect cheap multitouch 24" monitors.
Win 8 is Win 7 with a greatly improved Start button and a 30 minute learning curve -- that's without opening a single Metro app. Desktop apps work the same as Win 7.
Think of developing Metro apps as a chance to get into the iPad App Store lottery except Windows OS is a 9X bigger market than the existing iPad market.
Win8 also offers some performance improvements, most dramatically in startup. I can cold boot (pull battery out, replace, hit the power button) my shitty netbook in less than ten seconds, including POST time. It's got a single core Atom in it, by the way, and can't even play HD YouTube videos.
My old desktop came out of hibernation and became usable before my monitors turned on. I could move the mouse, then hit my macro to open Firefox and by the time the displays were warmed up Firefox was up and running with my tabs loaded in. This was using a six year old Core 2 Duo.
There are some major changes under the hood. Don't let the fresh paint job distract from the more substantial things lurking below.
all my computers are windows 7, i am currently holding a 50% off to upgrade to windows 8 in the fall when tis thing comes out, is it a good idea, or shoud i wait til probebly next year to upgrade
There are some good responses here, I'll offer my take on it. I do recommend that you DL the consumer preview and stall it on a hard drive that is roomy. Alternatively you can run it as a virtual OS.
I would not run out and buy it for all your PCs. There's nothing wrong with WIN7 and most folks won't care about the new features. If you plan to have a windows phone, tablet, etc then its a given that you'll want all your devices running the same OS.
However it is faster, especially noticeable with web browsers. I am enjoying it, but just recently I am noticing some stability issues and quirkiness. I gave up my WIN7 installation, but i am contemplating reinstalling since it has been giving me a few issues.