You should use WCF.

I'd like to give you something to think about:

A while back, a well-known figure in the Mid-Atlantic told a room full of people that they shouldn't spend one second learning web services. I realize you don't speak for this person (or vice-versa), but I'll say the same thing here that I said to him......

Sure, it's a no brainer that developers should learn the aspects of the .NET framework that are in use today - which includes WCF. But right or wrong, there's tons of legacy code out there using "older" techniques, and can't all be upgraded at once.

A sad but true fact of life is that some developers are successful in part becuase they're historians - they know what had to be done in prior versions. I know that over the last several years, I've had to use T-SQL 2000, ADO.NET 1.1, and web services. No, that doesn't mean we should all memorize the feature list of SQL Server 6.5. But in this context, I think a developer should keep in his "mental back pocket" how to create, host, and consume a custom ASP.NET web service.

Yes, every Microsoft website with information about creating web services also comes with the disclaimer, "you should create WCF services". But there can be times, even today, where the reality is that older functions need to be used. I'm sure it won't come as a surprise that across all the active Microsoft products today, some are still using web services "under the hood".

So to me, a reply of only "you should use WCF" isn't exactly a valuable reply.