OK, so I have been using the 1D Mark II for a bit now. It is a fairly decent camera for the price, but there are some drawbacks. Here is my wishlist.

More Megapixels

Since I take photos of birds, I need more reach. Since a 1200 mm f/4 lens is out of the question, some more megapixels (and a good crop tool) would be really really useful. I estimate I would get a 100% increase in keeper rates, if I had twice the number of megapixels.

Higher ISO

The 1D Mark II is not light-sensitive enough. In particular, any ISO setting above 400 results in noisy photos. It also makes it really difficult to take images on a rainy day difficult without a flash. I would like noise-free images at ISO 3200.

Sensor cleaner  

As the title says.

Easily accessible presets

I would like two or three programmable presets, so that I can have one for wildlife and one for indoors with flash. The programmable presets must also include C.Fn settings.

Autofocus

The autofocus works pretty well on the 1D Mark II, particularly when taking pictures of people. However, for smaller animals with a more random movement, there  is room for improvement.

Lens microadjustments

I really need this, so I can finetune the back-focus that I experience with the Bigma, without having to fork out US$200 each time I get a new lens.

A WAY Smaller battery charger

The battery charger that comes with the 1D Mark II is not only ridiculously huge, but the leads sticking out makes it extremely difficult to pack.

Gimmicks (most important first)

Larger LCD screen.
Easier menu selection.
USB 2.0
Bigger image buffer for approximately 40 RAW images.
Built-in Flash radio transmitter.
WiFi transfer.
Built-in GPS.

Conclusion

As you can see, all my wishes basically came true in 2009 when the EOS 1D Mark IV was released. This is one of the reasons I love Canon. They know what is missing and then they provide it (at a price, though – the cost of the 1D Mark IV is WAY HIGHER than the manufacturing costs – trust me, I have worked in Asia for a decade). However, if the rumours about the upcoming 1D Mark V is true, that will be the dream camera for me.