The bottom line is that having good tools doesn't make you any better at the job. Until you're confident that you can take good photos with the camera you currently have, you don't need a new one. If you want to become good at photography then use any camera; if you want to take higher quality pictures (notice that this is different to 'good' pictures) then get a DSLR. I can't stress enough that you don't want to get high-end gear and expect it to make you good. It won't. When you want to do things with your pictures which your current camera simply won't allow or when you feel you're taking excellent shots but the camera itself is stopping them from being perfect, it's time to upgrade. The only thing that looks professional or skilful about a poor photographer with a good camera is the camera itself.
Megapixels are only reference to the number of pixels captured in the image and don't effect how good it actually looks, just how much detail there is in it, and I sorta feel like the importance of having many megapixels in a camera is overblown given that most screens can't even display anything in fullscreen above 2.3mpx (putting this into perspective, the 3GS shoots at 3.2mpx, the 4 at 5mpx and the 4S at 8mpx) at a resolution of 1920x1200, although it does give you more detail to manipulate if you're working with it at a level beyond point-and-shoot. Having used both and being fairly alright with photography (lol immodest) I can certainly say that a DSLR will blow the iPhone to pieces in terms of image quality. But if you're good with an iPhone then the pictures you take will be better than those of someone who is bad with a DSLR (or any other superior camera for that matter such as the one you mentioned); again, skill > gear.
I always thought that the HDR feature was there to compensate for poor shots but made good ones look pretty dead and unrealistic. Preference, I guess. *shrug*