We were lacking an eating bar off the kitchen with chairs, the light switches are also lower.
The big deal if you get one - in our experience - was learning to "deal with" the shower. Its easy to get water all over the floor with a roll in shower, you need to pay attention to the curtain - and a few extra towels wouldn't hurt either.
With little kids, you may want to remove the knobs and/or burners from the stove. Always a good child saftey idea, even better when the stove is more accessible to little hands.
The studios lack counter space in the bathroom in addition to lacking a tub.