I was quite experienced with PHP but decided to learn ASP.NET (C#) to do this website. It has taken about 3 weeks to write a forum, blog and basic user/site management.
I've grown to like doing things in ASP.NET , but getting a good server and software for the server is a horrible experience compared to the linux route. It may or may not be obvious, but to run ASP.NET websites you need Internet Information Services (IIS) which is a Microsoft based web server, which means running Windows. The most common web server is Apache, and that runs on both Unix and Windows systems but that doesn't run .NET code.
Overall though I think the website was a bit quicker to do than it would have taken me in PHP, and I was learning a new way to do things at the same time. An experienced ASP.NET developer might have done it in two weeks. The whole website is seamlessly integrated in regards to users being able to post on the blog, post on the forum and manage other things.
A question people have been asking me is why ASP.NET? It merely has come down to increasing my experience. Being a C++ developer you can often be stereotyped as this dinosaur that doesn't want to embrace change. I code C++ though because it's extremely efficient and it offers great challenges, and while I do have some disdain for the modern "easy" languages they are there for a reason.