Should i upgrade to ios 7.1 on my iphone 4?

I just want to know your opinion?

No don't

NO! IOS 7 is the ugliest and worst iOS ever!
This is the first iOS not by steve jobs (iOS 6 he helped with, even though he was dead for release) and its worst again. I'm not an apple fan any more because of iOS 7. I'm sorry if you did.

No don't do it i heard that it doesn't work well on iPhone 4

Yes, eventually Apple will discontinue the iPhone 4, they already have with iPhone 3Gs, which means you won't be able to download the latest apps eventually, always update, you might not always like the update but there's always a good reason that updates are released.

Update, new apps are made for iOS7 only.