jujustad, the objective of a raised bed is to provide a volume of drained soil which would be a favorable medium for root proliferation.
Enclosing this volume on 4 sides with an impervious "wall" and lining the bottom with any kind of fabric will defeat this objective.
If it is worth it, you can drill (weep) holes in the sides of the wall close to ground level. This will facilitate drainage of the volume of soil above and provide a 'reservoir' of moisture in the volume below. This "stored" moisture can replenish the volume of soil above by capillary action.

Landscape fabric between two soil volumes will have a tendancy to cause water to perch above the fabric, in addition to inhibiting the natural wicking process through your medium, I would advise against it. Additionally, I would personally recommend using a variation of Al's 5-1-1 for your raised beds. Adding a second fraction of peat (or compost if you are so inclined) for a 5-1-2 will provide an excellent medium for that application. I am personally growing eggplants in a raised bed of this composition, and have never had better results.

PJ