... If you are talking about the GW resin (Finecast) I do not believe it will hold up over time as the quality of the resin is not as good as other resin items I have bought.

I am sure other people will be able to add more details about resin.

My first exposure to resin was Verlinden components for modifying Tamiya 1:35 scale tanks. They make a huge range, and have been around for a long time BUT bear in mind that this was for a modellers market rather than wargamers, so the finished pieces probably sit in display cases or display shelves safe from the bashing that gaming pieces will endure over time. I don't know anyone locally who has used much in the way of resin figures - plastics and metals are the standard fare - so it will be interesting to see what turns up. Looking at manufacturers like Hasslefree and McVey Studios, resin seems to be more for the modeller than the gamer - the same sculpt in resin is more expensive than the metal versions. Having said that, McVey's Sedition Wars stuff will be mostly plastic (oh yes - the first load of that will be landing at Schloss Dorthenstein before Hogswatch) and from what I have seen, the quality is fabulous. The original range was collectable resin - top quality but pricey. That range seems to be continuing with new sculpts.
Ask people with Forgeworld stuff - I have some components and they look fine still though they were not used as often as other bits and bobs I have.