Is it a good beginner's camera because it doesn't allow spot metering?
How many Canons do. And how many times is a person shooting one going to say "Ahh geez. . .I REALLY need to expose of that SINGLE SPOT!" For the beginner, Canons metering system should suffice for the majority of photos they could even bother caring about.
Is it a good beginner's camera because it only shoots at 5fps?
OH NO! Welp there goes any sports photography out the window. Certain no way anyone could grab action shots at five frames a second. D300 users may as well toss their cameras as well with the paltry one extra frame per second.
Is it a good beginner's camera because it has a plastic body and not a magnesium alloy?
I'm clumsy, so I need every bit of protection I can get! And Magnesium Alloy just SOUNDS cooler.
It is a good beginner's camera because to change the aperture you have to hold down a dedicated button and then use the shutter speed wheel?
"What's this MODE button on the Mark III. . .and whats it there for. . ." Great, you save one click. How revolting.
Is it a good beginner's camera because you own one and have never shot with anything else so you're just recommending what you know?
"I've used this camera and its great!"
"Liar."
"What?"
"You're a liar and dunno what you're talking about. . ."
"But, I'm speaking from personal experience!"
"You're still a liar."
I see why you choose the username. Not to be "ironic", but to deflect any criticism of anything you say:
"You see, my name - I called MYSELF that. Look how bold I am. No criticism you can lobby at me matters - mwahahahaha!"
In summation - do not listen to this toolbox. If you can find a good deal on an XTI/XSI/20 or 30D - get it. In the end you WILL get good images out of it so long as you KNOW how to use it.