The biggest benefit is that the code is more succinct. The VS editor will also have the itellesense support that some of the other view engines don't have.
Declarative HTML Helpers also look pretty cool as doing HTML helpers within C# code reminds me of custom controls in ASP.NET. I think they took a page from partials but with the inline code.
So some definite benefits over the asp.net view engine.
With contrast to a view engine like spark though:
Spark is still more succinct, you can keep the if's and loops within a html tag itself. The markup still just feels more natural to me.
You can code partials exactly how you would do a declarative helper, you'd just pass along the variables to the partial and you have the same thing. This has been around with spark for quite awhile.