What are the pros and cons of medium-density fibreboard (MDF)?
MDF is medium density fiberboard. It is essentially an amalgamation of sawdust, wood chips, and binders. Sorta like dried oatmeal.

Cons:


MDF is a pain to work with if you have to remodel later or install hardware several times, as the more you drill it, the less sturdy it becomes and begins to flake. 
It will also split if not pilot hole drilled.
MDF does NOT tolerate water well. Water begins to degrade MDF into fine particles, think wet cardboard. 
Smooth shank nails have a difficult finding purchase.
Formaldehyde resins are commonly used to bind MDF together, so I wouldn't use it near small children or pets. 
It is much heavier than similar sized pine boards. 
MDF crumbles easily, so finding pieces that have a clean edge are hard to find. 


If you have purchased anything from Ikea, you know what this is.  

Pros:


It's cheaper than hard wood.
It can look very "clean" as it doesn't contain knots or rings or any other naturally occurring wood deformities. 


Verdict: Use anything else, seriously. MDF is cheaper, but you will pay for it in the long run. Especially true for cabinets, as weight of the wood will decrease the amount your cabinet can hold, plus MDF will begin to sag from stress.

What about Pineboard? Pineboard, considered to be the cheapest whole wood you can buy. Is stronger than MDF, lasts longer, holds up to water degredation much better, and doesn't crumble.