Re: Ios 7.0.4 on iphone 4
I am using 7.0.4 on my 4. While it 'may' appear to be slower to run than on the newest iPhone, I have not noticed any degradation in operation from the last version - or in fact, from iOS 6. I have not turned off any visual effects and it seems to run smooth enough, without any noticeable delays or stuttering. The only exception to that is Facebook, but the app has traditionally opened and run very slowly on my 4 - but that's a problem I hear others have, regardless of iPhone, so I don't think that counts.
I leave wi-fi running and have not noticed any additional drain in battery - in fact it might be better.
Meanwhile, 7.0.4 seems to have fixed a Facetime connectivity issue for me - I wasn't able to actually use the service.
I hope this helps.