Under General Grant, how was the Union military strategy in 1864 successful or unsuccessful in the eastern and western theaters of the war?

Grant's strategy, formulated with Sherman, was an enormous success. The plan was for Grant to tie down and wear down Confederate General Robert Lee's army in Virginia. Sherman would enter Georgia from eastern Tennessee, liberate it from the Confederacy, and then march to the Atlantic Ocean, cutting the Confederacy in two again. (It had already been split by Grant and Sherman taking the Mississippi River and its ports.) Then Sherman would march to the north through the Carolinas, coming up on Lee's rear.
The plan worked remarkably well, proving Grant to be superior as a general and strategist to Lee. Grant was able to outfight and outmaneuver Lee from the northern part of Virginia to the peninsula on the coast and then pivot west to Richmond, from which Lee was expelled and the Confederate capital taken.
Sherman took Atlanta in a siege; the Confederates then ordered Atlanta burned down, only partly succeeding. Sherman then marched to the sea—with Confederate General Wheeler ordering everything in his path destroyed. To this day, the Lost Cause and other Confederate apologists blame Sherman for what Confederates did. Sherman only destroyed military targets like railroads and mills and gave Georgians receipts for the food taken to be later reimbursed by the US government. By the time Sherman reached North Carolina, Lee had already surrendered to Grant.
The main criticism leveled at Grant was that his victories were too costly—an opinion articulated mostly by those same Confederate apologists. Lee actually lost a proportionately higher number of men and ultimately didn't win against Grant.