I have an iphone 4s! Should i update to ios8?

I have an iphone 4s!
should i update to ios8?

Not yet, there's still a bug in the IOS 8 so wait until they fix it

If you have storage I heard its great

Your 4S might not run the ios8 very well, due to the 4S being older and much slower than the newer iPhones.

Yes.

Yes there would be a slow down but its not a drastic slow down. Fractions of a second in most scenarios.