Let's be clear here, photo editing and presentations don't need a beefy GPU and the HD 4000 does a fine job there, "gaming" is too wide and needs to have some variables defined - which game, at which resolution and with which quality settings.
You want to play older games or 2D/card games or Facebook games in a browser? The HD 4000 is fine for that.
You want to play Battlefield 4 at 2560x1440 with decent eye candy effects? It's going to be a slideshow, if the game even runs at all.
Those are two extremes, there's a lot of stuff that fits in between; as a general rule of thumb tho, for recent games at higher resolutions and settings, the HD 4000 won't cut it.
You can however reduce the screen resolution and quality settings to get better performance and, in most cases, you will be able to play most games in some capacity - it won't be the best experience ever, but it'll work.