Going semantic seems to be the right track. With the next revolution of the internet with Web 3.0 already dubbed as the “Semantic Web”. Google has been in the search field longer, and has much more data about people and their search patterns, so going semantic might not be as big a step for them. However if Microsoft has found the gaps present in the search engines of today and  aims to create a search engine that fills all these gaps, they need to make sure not to introduce any gaps of their own. With their track record of progressively incorporating more bugs into each subsequent product version, this is what might be their biggest challenge.