There are obstructions in Section 504, Row 1. However, Seats 6-9 should be able to see nearly all of the action. Seat 9 in Row 1 may have a slight obstruction from a column at the end of the aisle, but it is not directly behind the column.

Section 504, Row 8 Seat 106 View
The column in Section 504 at Wrigley Field