The first issue is safety. There are several options for securing the side of a cot bed. A typical design is the drop-side cot, where you open one side of the bed (some models will open on both sides) to lift your baby in and out safely. In the US they are talking about banning drop-side cots and cot beds because there have been problems with faulty catches on some beds. Of course if there is anything wrong with the catch then a drop side can be dangerous, but in Europe there is no suggestion of a ban and there seems no reason to think drop sides are usually dangerous. However, you may want to research this.
You also need to think about how long your baby will be using the cot bed - ie whether to get a larger one that he or she can grow into, or a smaller one if you are planning to change to a bed quite early on.

You can find more tips here.