If you have an iPhone would buying an iPad be waste of money?

I have an iPhone, and I'm thinking of buying an iPad. I would have already bought one, but I feel like I can already do what an iPad can on my phone. Would it be worth it?

Also, i can't decide, should I get the iPad 2, or iPad retina display? I know the newest is going to be the best, but is the retina display worth it?

It is basically a bigger version of the iphone. You get the same interface as the current iOS minus the phone. That said using a tablet is a completely different experience then from using an iphone. If you like reading articles online you're going to love the iPad since you can switch to reader mode and articles turn into newspaper like format, you do feel feel like you're reading an actually newspaper. Watching movies and videos are amazing since the screen is bigger, and playing games is so much better on the iPad. Only you can tell if the Retina display is worth it. Personally compared the iPad 2 and retina model at the apple store and the retina display looked a bit better, but definitely not a night and day comparison. I personally went with the retina display because it was a more recent release, love it.everyone needs to get an iPad.