IrfanView is showing you camera-processed image (embedded in the raw file by the camera), whereas ACR is showing you, well, ACR-processed image. You need to learn how to set up defaults and edit to please...
Edit: IrfanView is also showing you an embedded preview of the DNG, but it's the default rendering of ACR instead of camera.
All experienced ACR users can accomplish superior results than camera-jpeg. However, initial rendering needs some help, and also there is a psychological factor: you're used to the way the camera renders things, and so it seems more right...