I'm a cabinet maker by trade and i've made countless tank stands and hoods for people out of the veneered and plain mdf, my local fish shop build and sells tanks stands and hoods out of mdf, without a problem.
As long as you do the job right its a fantastic material to work with, the trick is to sand all edges with sand paper going down in grades until its as smooth as glass, then seal the hole thing with a undercoat.
Once you have done this use a decorators cox (flexible filler the type you get in a tube to use with a silicon gun) and run a bead along all the joints to seal them and then paint with two to three coats of your paint, the same method will work with stain and varnish.
Another thing that is worth doing is putting a dad of silicon on all screws before screwing them in, this seals the wood, and a dab on the head will stop rust there to.
Its true that mdf cabinets don't last as long but this tend to be more because people don't look after them, water will damage solid timbers if not cleaned up.