Right here comes the broken record moment...
There's no such thing as a 'healthy food' just a healthy diet
No such thing as a 'bad food' just a bad diet
I like to look at carbs, fats, proteins as a hybrid engine in say a Toyota Prius.
Carbs are your high octane fuel source (petrol)
Needed when active, working hard and you want performance.
Fats and proteins are good to use as a fuel source when at work, walking, chilling out etc
So is porridge a healthy source?
It depends on your lifestyle and the demands and requirements YOUR body needs.
If you're active and require so many carbohydrates to get through the day, absolutely crack on, bang some fruit in too - enjoy it.
However if you're planning on being sedentary perhaps look to another choice
Carbs have one job and one job only, to provide energy.
If not used, they'll be stored.
Which isn't as bad as you think
However make considerations for what you eat each day