Both the square and rounded SQs are significantly forgiving clubs with large faces. Shafts contain strong kick-points, and the grip feels good in the hands. Despite the unique shape, SQs set up well and feel fairly comfortable at take-away and the top of the swing.
Players used to working the ball might opt to forgo the square model--the construction prevents some players from turning over the hands to draw the ball. Both models are a bit light, and players might prefer something with more weight. While both can produce penetrating shots, there's a tendency for high shots as well.
Despite the Tiger Woods seal of approval, both models slightly lack in performance. Players willing to give up distance for accuracy will find success with the square model. Shot shapers might look for success and comfort in the Ping G2 or the new Nike SQ Dymo models.