Personally, I feel it is WAY too overly complex, and too ambitious, relying on rocket sizes/power that greatly exceed even the Saturn-5, in order to bring huge teams of hundreds of people to Mars.

But... if anyone can do this type of impossibly sounding mission, it is certainly Elon Musk!

Still... I fear he is finally getting far too carried away here...

Personally, I think he should scale down the FIRST mission, and just get a team of about 4 to 8 people to Mars, for a 1 year stay.

With that mission we will probably be able to answer key questions such as whether or not there is current alien-bacterial-scale life on Mars right now (or past extinct fossil life), along with what it is like to truly live on Mars, whether you can grow things in Martian soil, etc...

After that mission (which may or may not discover true alien life), Elon Musk and his company SpaceX will be an ultra-true super hero... and people will throw even far more resources and money at the company and it's goals.

And then he can do the super-rocket thing and try to bring hundreds of colonists to Mars.

Also at that point, another option would be for him to focus on an asteroid mining project which could generate billions upon billions of dollars worth of rare metals, which he could also use to found a more elaborate town/city on Mars, with lots of greenhouse food growing domes, etc...