Like almost everyone else here, I put off buying a premium combination square because of cost, and made do with cheaper combos, simple engineer's squares, various rules, etc.  Further, I hesitated because opinions on Starrett's quality varies among machinists and from tool-to-tool.  Many prefer Browne & Sharpe or Japanese lines like Mitutoyo.  In the end, I finally broke down and bought the Starrett, really as much because it's the only commonly-available premium combination square as for any other reason - and couldn't be happier with it.  It is accurate and smooth.  It's actually one of those few tools where you feel the quality every time you pick it up.  It's a pleasure to use it, so much so that I intend to pick up one of the 6" versions as well.