No, it is not worth it. As a general rule of thumb as well, I would be wary of any company which used ads excessively, especially if they make unusual promises. The normal, pervasive payment model for talent search companies is to charge the employer a significant fee (e.g. this fee is in the $10k-$50k range for lateral attorney jobs). This is also the case with TheLadders.
So, instead of using the multitudes of services out there which are free to the job searcher, you can instead pay for the privilege of using TheLadders.
There are some job search sites which scavenge the net for job postings on company sites, that only are charging the user a fee, instead of the user and the company, but that is no the model of TheLadders. Those sorts of sites tend to have a huge number of postings, if they are good, and provide some actual added value, since a company is more willing to hire someone when they don't have to pay a substantial fee to get help "finding" them.