I've loved AD since I started working with them in 1998. DirectSoft has its problems, but its come a long way in the last couple of years and version 5 should be out soon which from all reports will make it a lot more robust, especially on math.
From an ordering stand point I love that I can get on their web site, spend 10 minutes to order parts for 25 control panels, and have them tomorrow morning. None of the local suppliers here could do that... It would be a 30 minute phone call (at best) and a minimum week delivery (if not two). To keep my local customers happy I just carry some inventory of PLC parts, with the AD pricing I can afford to have parts for a couple of complete control panels just laying around. For customers that I'd have to ship to anyway we can drop ship the parts directly from AD and know they will be at the customer's door the next morning.
From a tech support side I love that they LISTEN. They're easy to get a hold of, but the biggest difference (to me anyway) is that they'll actually listen to my issue and what I've tried to correct it before starting to spout off 'solutions'... The few times when the tech I got on the phone couldn't help me they connected me with the engineer that designed X, Y, or Z part.
OK, enough ranting about the greatness of AD. Oh and just for the side note, yes there is a whole lot that the AD won't do or won't do gracefully that you can do with AB, etc.