I really like the ability to compare products in Argos website, it helped me make an informed decision on the purchase I was making by using that and checking out the customer reviews. Easy to select where to pick up the items as well and it's useful having the order numbers text through, saves searching for emails.
I used the fast track service for Argos which was pretty pointless as everyone else got served before I did in store. Instead of it being faster, it was in fact slower than going through the traditional system.