I very much love raised bed gardening for several reasons.
1. don't have to lean over so far (ewww my aching back)
2. Have a convenient place to sit to weed
3. Beds warm up better giving you longer season early in the year and later in the year.
4. drains well so roots of plants are in standing water
5. soil is not trampled and compacted due to foot or tractor traffic
I used concrete blocks for my raised beds. All my beds are approximately 4foot wide by 20 foot long. At 4 foot I can reach the middle from both sides of the bed and not have to worry.
I put down cardboard to keep the weeds down to a minimum and it last about 2 years before it starts breaking down. Its safe under USDA Organic standards to use.
I then fill them up with a layer of aged compost then a layer of topsoil followed by another layer of compost and another layer of topsoil. I do this until its filled to the top.
The holes in the concrete block are good for putting pvc pipe and bending it creating a hoop. This is good for draping floating row cover or greenhouse plastic over to extend your season. The floating row cover keeps the frost off as well as keeping the flea beetles and other pest away from your crops.
Here are a few pics.
This first one is the backside view from the woods. I have to fence everything in because of the deer and rabbits as I live in the woods.
The back row goes all the way across this is good for beans to grow up the fencing. It is also 3 foot wide since I cant reach it from both sides It had to be made narrower. The other two beds are both 2 blocks high. It takes alot more soil to fill them in but its worth it for deep rooted crops like carrots and the like. its also nicer since it just right for sitting height and not having to lean over as far.