WMI vs Windows APIs

The main disadvantage of WMI is speed, it is slow to query data and if you are trying to use it during start up it can delay you starting as the WMI service takes a long time to come up.

However, WMI information is richer, as in you need to sometimes make several API calls to get the same amount, some information is a lot easier to get at and the filtering syntax can dramatically reduce the amount code you have to write.

If speed isn't a massive issue, I would always lean towards WMI.