Half Smiles of the Decomposed (Matador), apparently the final Guided by Voices album, contains further evidence of front man Robert Pollard’s recent conversion to production values, and the three-minute “Window of My World” is about as close as he’s ever come to writing an epic song suite. Otherwise Pollard’s going out like he came in: same magnetic-poetry-kit titles (“Sing for Your Meat,” “Sleep Over Jack”), same earnest, off-key vocals, same utter reliance on jangle pop and the Who as songwriting models. Same inconsistency too–no rock act worth loving has a worse success-to-failure ratio, and most casual listeners understandably gave up after, say, 1995’s Alien Lanes. But even if GBV has been wrong half the time, that still leaves roughly a million snippets and anthems where they got it entirely right, and a smart distillation like last year’s 32-track Human Amusements at Hourly Rates packs the slovenly ambition of a one-band Nuggets–heard in the proper mood, it sounds like all the rock ‘n’ roll you need. The Metro shows tonight and tomorrow, both sold out, are billed as GBV’s last ever, and the farewell tour has been promoted with jokey slogans (“Mission: Accomplished,” “The Electrifying Conclusion”) and stunts (getting cities to proclaim an official Guided by Voices Day). Which feels about right; sincere attempts at closure are for self-important types who worry too much about their success-to-failure ratio. Former GBV member and Pollard songwriting foil Tobin Sprout opens. Thu 12/30, 10 PM, Metro, 3730 N. Clark, 773-549-0203 or 312-559-1212, sold out, 18+.