We run a tiny internet cafe and have been trialing Vista for roll out. Of the half dozen initial machines only one is left, which will probably be rolled back very soon - or converted to Ubuntu.
Issues that have plagued us:
High hardware bar (2Gb minimum to make it work)
Unreliability (reboots randomly across a variety of machines)
Incompatible with existing domain structure (How can MS release an OS that is incompatible with Small Business Server???)
Scripting - all the boot scripts have to be re-written
Group policies different
Security stops many bank sites from working
Network performance stageringly slow
Printing? forget it... Vista printer drivers are a nightmare... Which default printer do you want today?
and most importantly - Customers don't understand it with all the changes
Unbelievably 3 machines were destroyed oy the OS! mostly it appears to be heat issues, popping motherboards, power supplies and graphics cards but Vista appears to thrash and trash hard disks. we found once a PC started rebooting itself regularly you could chkdsk it and it would be fine for a couple of weeks then start rebooting again. you could go around the cycle a few times then the hard disk was trashed. New hard disk... ring MS to allow you to reinstall the OS and off you go again. After 3 hard disks on one PC we gave up and went to ubuntu... it's been fine since! but the others we gave up on the 2nd hdd and reverted to XP.
So we have had lots of problems. I am in business, I have to make money from these PC's and I don't really have the time to mess with somebody elses half finished experiment - which is the excuse I have been using for years about Linux, but now I am applying that argument to Vista. We have now largely gone back to XP which works predictably and is easy to manage in a group manner and interacts well with the servers.
If we go to Vista we will have to upgrade or replace the client PC's and more importantly upgrade or replace the servers, then spend half our time explaing to customers where everything is...
Interestingly enough we now have a few Ubuntu machines. Visually the OS is gorgeous - actually better than Vista, it's come on a long way in the last couple of years and I didn't really realise how far it had come on and what I was missing. It seems to have much better security and I can tie it down more easily. It's also easier to rebuild (no license keys means I can just dupe the disk and boot!) What do the customers think? well, those that notice mostly have issues with firefox (bank and complex sites - or Active X) the rest are amazed it's free! Oh and the office apps all look like office 2000 (How often do I hear where is the print button on office 2007?) If only I can work out something like group policies and user management like Windows domains!
I could stay with XP for at least 2 - 3 more years before I have to decide, but I could upgrade all the PC's (or buy new) and install Vista, re-learn all the management, applications and PC build methods and put in a new server... or ... I can keep all the PC's as is and install Ubuntu once I have learn't how to group manage them... Hmm, I get to dump all the MS licensing costs as well... Oh and all the office applications look the same so my time spent supporting users would be less...
I could write an article on this... ah, I nearly have!