Welcome to Flyertalk.
When joining a Flyertalk section please use Search this Forum function to look for previous discussion of the same topic. Here are some threads I found using the keyword: venture.
http://www.flyertalk.com/forum/other...-one-card.html
http://www.flyertalk.com/forum/other...e-rewards.html
http://www.flyertalk.com/forum/other...-why-hate.html
When comparing Capital One to other programs bear in mind that Capital One "miles" are actually points worth a fixed amount, $0.01 each. The value of airline miles is widely debated on Flyertalk, but a mile can be redeemed for greater than $0.02 each. This means that Venture "double" earnings merely makes it competitive with cards that earn one airline mile per dollar, but many cards earn more.