The iPad has been one of the best purchases I've ever made. I absolutely love this device. It is my first choice, my go to device, for everything it is capable of, and has provided some functionality in my line of work that no no other device can fulfill, or at least not from a practical sense. If I didn't own one already, and knew what I knew now, I would buy one today, because I wouldn't want to go the next...8 or 9 months perhaps without one.
However, if you don't have a burning desire to get one and are already obsessing about the features you might miss out on in the next version, maybe you should wait. You could always buy now, sell it later and therefore upgrade for a relatively minor fee. Apple products hold their value very well.
I don't really need much more out of my iPad than what it does now. Of course, I wouldn't turn away speed, ram, storage increases, retina display or the like, but those things would be relatively minor improvements to a device who's form factor has already drastically changed the way I use my computers.