Best backup option? Is Time Capsule worth the investment?

I'm currently doing some work that is vital and I cannot afford to risk losing.  Presently I backup my MacBook Pro using an external hard drive, however, I am not the best at remembering to do this so I'm looking to invest in an automatic wireless backup option.  Time Capsule is the obvious and simple answer to this question but it is also a pricey option.

Are there any Time Capsule users who would recommend it? Or is the general view that in 2011 the best approach would be to invest in a monthly subscription to a cloud backup service?  I have quite a large amount of data to backup so none of the free services are really an option.