Love this repository of interesting artefacts. Did you know that the original Queensland Museum was in William Street then shifted to that magnificent building in Bowen Hills? a highlight of my childhood was visiting the latter with Dad and my primary school teachers.
Yes, we regularly visit QM and there is always an interesting new exhibition to discover. The current Deep Oceans exhibition is well worth a look - be prepared to learn a lot about giant underwater creatures and kids will love following the Octonauts self guided tour.
While not at the standard of some other museums in Australia (such as Sydney's Powerhouse museum) it does manage to provide a range of interactive activities in its exhibitions, especially the non-permanent ones.
For adult visitors to Brisbane, the Brisbane Museum is a better option because it provides a historical overview of the Brisbane area, but the Queensland museum is great for kids (including kids visiting Brisbane).
The last time I went there was when my friend came up from Sydney with her son. It was a very hot day, so I could take them to enjoy the air conditioned museum and then swim at South Bank.