There's a prevailing opinion that Windows 7 is a big improvement on Vista -- but my own experience of the Windows 7 RC so far suggests that it can be just as bad, if not worse.
I've come to the RC late relative to its appearance, in large part because I was doing the Hand Luggage Only project during May and didn't want to burden myself with an unsupported OS on the road, even in a dual-boot environment.
I'd been running the beta of Windows 7 on a spare machine, and had largely been impressed: it ran faster, seemed to have fixed some of Vista's more egregious faults, and didn't have a UAC implementation that made me want to throttle people. True, it wouldn't actually let me submit any feedback, which didn't bode well for online activation, and it had some problems with USB, but it was a beta after all.
For the RC release, I decided not to do the downgrade back to Vista on the same system, and instead opted for a clean install. I wanted to see how well Windows 7 would handle recognising an older machine from scratch. Sadly, the answer turned out to be "not well at all". On a ThinkPad T61 -- a machine that's only a couple of years old-- it came up with five unrecognised hardware items.
However, that wasn't the biggest issue: networking was. My predominant complaint about Vista was its poor handling of wireless networking. My very first Vista machine had major wireless networking issues, and just in the last week I had to go through a convoluted correspondence with Microsoft to get my newest Vista box to successfully communicate with a bog-standard wireless router.
I'd had no problems connecting to my home network with the beta of Windows 7. However, once the RC was installed, it spectacularly failed to get any kind of working connection whatsoever, alternating between the familiar exclamation mark (meaning "you're screwed") and no connectivity indicator at all (meaning "you're screwed, but hopefully you won't notice"). All this was on a router with which I've successfully hooked up not only the Windows 7 beta, but Vista, Xandros and iPod Touch devices as well. Even when connected directly via an Ethernet cable, it refused to talk, suggesting that Windows 7 sometimes effectively treats a working networking stack as its own personal slaughterhouse.
I've never been a fan of the Vista "diganose" feature, but compared to Windows 7, it's starting to look like a mine of information. After grinding away for some time , Windows 7 simply said "Troubleshooting couldn't identify the problem" -- despite that bright yellow exclamation mark. Even Vista had the manners to suggest resetting the wireless card or getting a new IP address might help, even if it rarely did.
One swallow does not a summer make, and I realise plenty of people have managed to get Windows 7 to connect to wireless and wired networks without a moment's pause. But the fact that the RC -- which is meant to be much closer to shipping code -- has lost the plot so badly in my case with a fresh install suggests to me that the honeymoon might not even last until the October release date. Frankly, the idea that you should never use the .0 release of a product sounds more appealing than ever right now.