Integrated ordering with suppliers is one of the great features of open.  However I have noted a large deficit.  

Over time its common for backorders in the system to get well out of sync with the supplier - this will lead to failure in the order generation phase because it cannot correctly calculate backorders on current stock.

I will refer to 2 backorders - internal backordering, and supplier backordering.

This occurs for 2 reasons

1.  internal back orders are not tracked in the ordering screen - ie a read only field showing how many of an item you currently have on backorder.  This means when an item doesn't arrive and the supplier places it on the supplier backorder - the result is the systems internal order remains partly filled - creating an internal backorder.  However while it might not be the next order - staff will likely note the empty shelf and manually order the item on top of regular generation.  Likely due to historic second checks on the internal generation.  

2.  No workspace exists to manage backorders collectively.  

I think improvements in this area would greatly improve the reliance on Order Generation.