now, im not trying to attack you, but can you name a few software that is not working on 8? because I have not seen any of my program stop working so far, just curious may be I can help out
as for speed... I don't really understand why it would be worse if you had vista before? 8 uses the pretty much the same amount of resource as 7 and 7 uses a lot less resource than vista, may be a bad driver? (my upgrade was from 7 to 8 so haven't felt any improvement or degration other than the much faster boot speed)
as for connect to every pc automatically, did it give u the option to say yes or no? because when I upgraded my desktop it did ask it, and the concept behind it was really because network neighborhood kept getting bashed... it still doesn't work as good as I hope it could be, but it's an improvement and if you don't want it, it can be shut off if you don't want it
I agree with you on Defender, at least to my understanding it's only job is to check system files to make sure they are good, not meant to be antivirus