Depends what you are taking a photo of.
I reckon landscape and still moving things, then MF is no probs. For (active) kids, not the case!
I've got a D3000 with a 50mm 1.8D, and while it's a great lens (and v cheap), I get very few keepers of my 3 year old (unless sleeping!), the 3 month old is a bit easier - sometimes

That's why I've recently bought a 35mm 1.8 AFS - makes life a lot easier!!
MFing can be hard work for certain things, make no mistake - yes, rewarding when you get it right, but life is short

I can't see any optical differences between them, but I'm not a pro and dont want to be, my aim is just really good photos documenting the kids lifes....
Different things for different uses.....like all photo gear
PS. The change from focal length was for different reasons, and I could have got a 50mm AFS but felt it too long for my needs, so don't read into that so much....