The standard futon frame is back loading. This means that when you close the frame, you must close it from the back. Depending on the futon mattress you choose, especially if its on the thicker side, you may struggle slightly more when closing the frame. Keep in mind that if its a back loading standard frame, you must have the frame a few inches off the wall in order to convert it from sofa position to bed position. Also you need to have a little room on the side in order to close it from the back. This means if you have side tables or book case, it may be a little cumbersome to close the frame from the back.
When deciding on a futon frame, you have to take a few things into consideration. Will you be opening and closing the frame quite often? Will you use it as a primary bed or long term temporary use? Do you have just the right upper body strength to operate your futon frame?