The two main competitors I would "stack up" against Taleo are "Fieldglass and IQNavigator". I would rate Taleo above Fieldglass but slightly below IQNavagator. Fieldglass is harder to search through thus making it harder to search for positions and candidates. IQN is a bit easier with the overall reporting and it is easy to set up email alerts.
I would start out by saying ALL VMS systems have their flaws. I would recommend Taleo highly because I think the overall organization is strong. We are able to run reports easily and generate key metrics to keep the recruiting staff up to speed.