Todd McCarthy in Variety is merciless:

No doubt it will be back to the drawing board for “Che,” Steven Soderbergh’s intricately ambitious, defiantly nondramatic four-hour, 18-minute presentation of scenes from the life of revolutionary icon Che Guevara. If the director has gone out of his way to avoid the usual Hollywood biopic conventions, he has also withheld any suggestion of why the charismatic doctor, fighter, diplomat, diarist and intellectual theorist became and remains such a legendary figure; if anything, Che seems diminished by the way he’s portrayed here.
[…]
The demanding running time also forces comparison to such rare works as “Lawrence of Arabia,” “Reds” and other biohistorical epics. Unfortunately, “Che” doesn’t feel epic—just long.

The harshest graf:

Oddly, “Che” seems more about denial of audience expectations and pleasure than it does about providing the intellectual and historical heft that would serve as a good alternative. Soderbergh withholds much in addition to dramatic modulation, narrative thrust and psychological insight: A feeling of revolutionary zeal, the literal transformation of Ernesto into Che, his marriages and family life, the depiction of the entry into Havana, Che’s oversight of many executions after victory, the Cuban missile crisis and Che’s wish that nuclear missiles be immediately fired at the U.S., his mounting distaste for Russians, his obsessive diary writing, his “lost year” as a failed revolutionary sparkplug in Africa before heading for his fatal misadventure in Bolivia, and even the famous photograph.