Well, some said that HTML5 is the alternative for startups, but for a long term you should do native apps for mobile.

Others say HTML5 with responsive design is the "solution to all problems".

What do you think?

You see HTML5 is a great tool for developers and it maybe become the defacto mobile programing language but for the time being it isn't fast enough. Even on a powerful browser like the BB10 device it lags like hell. So i say native apps are the way to go

HTML 5 ia great for normal websites and to make website responsive. It's good as a solution for mobile users, but not a replacement for an native app. Though, they should keep the responsive version, even when the app is live.

But what I like more is html5 being a replacement for Silverlight, Flash and (partly) Java.

Be bold and create games like Angry Birds with HTML5, but please do not create apps with it. A minimal amount of border-radius, box-shadow, etc, is acceptable. All else, think about the kittens!