I work in risk management for a financial institution. And although I'm on the "business" side of things, I do have to develop a lot of applications for own quant finance work. And frankly, to my team subsets of WCF (like for example, DataContracts) are becoming invaluable.
Most of the comments I see here mention a JSON API or some other "REST" architecture suitable for a web app as a better alternative. This gives off an extreme "let them eat cake" kind of vibe. Seriously, there are other kind of systems than web apps. Having a way to strictly define your interfaces and your data flows, having an ability to quickly validate data that you get and communicate which kind of data you want is extremely important in situations where correctness of the result comes first, and you don't have control over the whole system landscape.
Most of the comments I see here mention a JSON API or some other "REST" architecture suitable for a web app as a better alternative. This gives off an extreme "let them eat cake" kind of vibe. Seriously, there are other kind of systems than web apps. Having a way to strictly define your interfaces and your data flows, having an ability to quickly validate data that you get and communicate which kind of data you want is extremely important in situations where correctness of the result comes first, and you don't have control over the whole system landscape.