It seems this material is harder to work with and is very fragile. Why make a kit out of it. What advantage is there to it over a normal model plastic? What are it’s drawbacks compared to normal polystyrene? I have not worked with it yet, but it seems like it’s more work with little gain.

Resin isn't harder to work with than plastic...just different....once you get to know how....if it's a well manufactured kit.....it's a joy to build.
Resin is used over plastic because of the cost of making moulds......a mould for a plastic kit can cost several thousands of dollars......the cost of a mould for a resin kit is a few bucks....this is why popular kits are usually made from plastic.....the manufacturer is confident they will sell many more than the cost of the expensive mould so they will recoup their output plus make a profit......resin kits are usually stuff off the beaten path...for instance British WWII armoured cars are rarely found in plastic.....but always found in resin.....because the manufacturer wants those of us that want them to buy from them....but also knows there aren't going to be an overabundance of orders....whereas a plastic kit company would know that if they spent the high dollars to make a mould they aren't going to sell the amount needed to make a profit within a short amount of time. I was once told the best selling Allied subject sells worse than the worse selling German subject....then we wonder why all the new releases are German!!!
I hope this clears it up for you a little.

You get much finer detail with resin than you will with plastic. As far as drawbacks, price, it can be fragile, and resin dust isn't the healthiest stuff in the world.

As grasshopp12 just said, the detail is finer, but also thescupltor can get deeper "cuts", i.e., a part of a uniform or other part that has detailing where a plastic could not due to the nature of the molding process.

And they look cool.

Nate

I agree with both Jeff and AJ.

Because it turns out better than plastic, and it drains your wallet or purse faster.
Thats about all I can say!

~Chip :-)

resin does have some drawbacks. The model is heavier due to the fact that several of the pieces are usually solid like tank hulls and especially ship hulls. The material is prone to sagging. I saw a beautiful model of the HMS Hood done in resin with the bow sagging about a quarter of an inch due to weight. The other problen is you have to carve small pieces off of the stumps vs clipping them off of spues. They are also usually more brittle