Should I get cydia on my iPhone 4?

Now… Or shall I wait till I get my next iPhone which is the iPhone 6 when it comes out. Are there any side effects? Is it safe for the phone? Can i delete it if I want to?

The number 1 rule of jailbreaking is that it WILL void your warranty, so be wary of that.

I have personally jailbroken my iPod, and there are no 'side effects' that will occur. All that it means is that you will have more freedom within your device and you will be able to add fancy effects and some useful apps that you usually couldn't get on the App Store.

As long as your warranty has expired, then sure, go for it. Yes, jailbreaking can be undone, but it requires a factory reset from within iTunes. Make sure you back up your device before jailbreaking.

Hope this helps.

It voids your warranty and you go through hell to undo it. I've done it to an old iPhone 3G. But I'd never do it to my current iphone.