Is ios7 compatible with iphone 4?

I don't know if i should update my iphone 4 to ios7 will it get slow?

Yes it is compatible. The new iOS 7 will work on any of the following devices: iPhone 5S, iPhone 5C, iPhone 5, iPhone 4S, iPhone 4, iPad 2, iPad 3, iPad 4 or iPad mini.

Yes it is although it won't be able to offer all the features such as Siri.

Yes it is but it will slow it down, the iphone 4 has an A4 chip and it is not well equipped to cope with ios7, some people are saying it has slowed their phone a lot and others don't mind, you can update it, try it and if you don't like it go back to ios 6 though.

I have the 4s with A5 chip and it slowed that down, it is bearable but I was going to go back to ios 6 because I preferred the speed of that but I'm due an upgrade so have taken it, my daughter is having the 4s and says she is happy with ios 7 on it.

I say try it, if you don't like it you can go back.

Not in my experience with it. Runs much better than I expected.