The quality of the Matchbox toys varied greatly. It all depended on whether the toys were made for Matchbox, such as the cheap plastic VF-1, the hovertank, and the Invid Shock Trooper; or if they were just the Japanese toys in new packaging, such as the SDF-1, and the die-cast/plastic destroids.
I never owned any of the cheap plastic toys, but some of my friends did. For the most part, they were just pretty ugly and lacked detail, but from what I recall they pretty sturdy.
I still have the only two destroids that I bought, the Tomahawk, and Defender. Sadly, the Defender is missing the gun barrels on its right "arm". Both toys were actually made by Bandai.