Well, I hate to break it to you, but Apple will most likely definitely release another iPad next March (or around that time frame), and it will most likely be better than the new iPad (iPad 3) that was just released last month. No getting around it.
That said, I've had every iPhone since the first one, and I've always though of the iPad as basically a big iPod Touch. I thought to myself "why would I need a bigger iPhone?" I didn't buy the iPad 1 for that very reason. I also didn't buy the iPad 2 for similar reasons, but mainly because the cameras stank, and that it didn't sport a retina display at that time, which had been rumored.
i new iPad (iPad 3) though, I finally broke down and got one. And honestly, it's been absolutely great. It's definitely a device somewhere in between a PC and my iPhone. You can use it in ways that you just can't use the iPhone, or use a laptop. It's super portable. Great for meetings., taking notes, writing e-mails on the go, etc. And the new Retina display is definitely worth the price over the iPad 2, at least it is in my opinion. The retina display was a HUGE, absolutely HUGE selling point for me.
It's definitely not a replacement for a PC or laptop, and it's definitely not just a big iPod Touch or iPhone. It does reside somewhere in between, but I still find myself having trouble describing just exactly where that is, probably because the concept is still so new. Overall though, I've extremely happy with my purchase of the new iPad, and I can't think of any specific reasons not to pull the trigger and get one if you're already seriously considering one. I think it's great!