Windows 8 is a mixed bag of fruit, plain and simple. I have already done a bucket-load of installs and a few upgrades. The upgrades found themselves nuked due to low performance.
The big suck of Winblows is that the OS was rushed, it has not had time to mature before release leading to why admins the world over stay away from an OS until it is service-packed.
I use Win8 across the bulk of my servers and PC's at home. Metro is the second thing nuked, all the bloat (apps) are uninstalled first.
I have come to the general impression driver support from MS is in the gutter. Out of the box, Win7 was bloody great at working with just about any hardware, sadly, win8 needs coaxing a lot on even new hardware. UEFI boards I have found to give more headaches and certainly no performance gain that UEFI was supposed to yield.
The only hardware platforms I have seen positive performance boost was the AMD FX81XX, Intel platforms run just as fast on 7 as they do with 8.
One of these days, M$ will fix their mess with lsass.exe leaking memory, I have had it with bloody M$-based forums with admins living in denial. There are claims that client PC's running win8 cause the host system to leak and is looking at killing QoS out of the clients stack, I can tell you, it is bullshit. The only way I have temporally fixed it is to rip out drivers M$ insist are the latest and greatest for the RealTek NIC and use generic Realtek set. Mind you, the hardware ID doesn't match, the NIC is a 8111B but drivers show it as 8168 from memory. The catch here though was it wasn't just drivers, I have had to kill off the PageFile as this left on seen the blow-out return at random times. Running the system for a long soak to see what happens. The other win8 servers don't have this issue, they just suck at networking and shares.
If someone finds a way to stop win8 trying to act as though it is on a domain, please let me know. Sick and tired of having to use credentials to access shares on win8 hosted folders from win8 machines. Win7 machines rip straight in without the headaches. While on shares, what wanker at M$ decided we need so many hidden admin shares? I am tired of either manually killing them or having to permanently remove them. This comes from hardware media-players that flat-out refuse to see anything on the network while a win8 system is broadcasting these admin shares.
Server 2012 is a plain mongrel to share files with, have blown a few installs away in the past. They just refuse to do plain sharing.
Storage Spaces is the only use I have for win8 on my servers (I don't run server due to above comment), seriously looking at FlexRAID on a win7 system soon. Even with my tweaks to the Parity and seeing 60-70MB/sec writes, the writes are still to slow for my wants/needs and combined with sharing mess, it's days are numbered.
WMC is nothing special either, I managed to get it working on a couple of systems (what twat thought to sell it as an extra????) but it is the same as WMC7. Still a pain in arse to get CODECs working to output the correct streams.
Boot times, oh yeah, lets rave about fast boots: um, NOPE. Yes it is fast but this is thanks to it just paging the kernel/core to the HDD's now slowing down shutdown. If you have moved to the modern age and running SSD's, they boot win7 just as fast. If your boots are slow on anything, clean out your bloat/junk. If you are on anything doing a serving role, look for the hacks/mods to kill off the fast booting bullshit, leaving it on just keeps any of the bugs for the next time the system starts meaning you have to REBOOT to clear it fresh. Proved this with the leaking lsass.exe that just keeping staying full after manually shutting down before server crashed.
Win8 works well for the home PC or Tablet. I would not suggest it for business or main systems unless you have the time to fix it all the time.