If you're due for an upgrade I would do it. To say the least it's really light, the taller screen is nice to have, the thinness feels and looks nice, it's a quicker phone, and it's tougher.
I have a 5 now, but I do still have my iPhone 4 with a can of soda resting on it, it's completely smashed both at the front and back, the screen literally (and I do mean literally) has zero visibility now because it's way smashed. Dropped it carelessly a ton of times and once slammed it to the ground on purpose out of anger and that's what finally did it, before I did that though I did have the thought in the back of my mind that the 5 was coming out in a matter of weeks, so I said why not.
Because of your 'dinged' screen and I'm assuming you meant slight crack you might be able to sell your 4 for around $100 less compared to what you would normally find for a used 4 currently in the market. That's just a guess with the presumption that screens can be repaired for around $70 from a third party which the buyer would most likely take into consideration before buying an iPhone 4 with such damage. Maybe the cost of repairs and parts will go down now because there's a new model? I don't know. A confirmation would be nice.
