A recent study analyzing differences between ATW and Google, claims ATW to be a sounder engine:
The objectives of the test were to evaluate in practice how ready each of these two search engines are to host user searches of a target site and how efficiently each search engine would reveal a target page on that site using known search terms that people have used already to get to that particular page through a search engine.
Google shines in listing fresh material, while AllTheWeb shines in getting a listing of every page in its listing time period. Should AllTheWeb increase the number of visits to sites, it would have a much more accurate listing than Google
ATW seems to come out pretty good:
AllTheWeb just needs to increase the frequency of their robot crawls and Google would have some formidable competition. AllTheWeb could, it seems, give searchers in practice a more efficient service than could Google.