I think one could certainly make the argument that the poem does glorify war. Analysis of the poet's word choice backs up this interpretation. Although the speaker uses phrases like "mouth of hell" and "jaws of Death" to describe the situation into which the Light Brigade rides, descriptions like these are figurative. They do not conjure a mental image of what war looks like, nor do they describe how death at the hands of another soldier would feel.
The reality of war is not described in any realistic detail. Tennyson does not touch upon the bloodshed, the potentially slow and agonizing deaths of bodies bleeding out, the pain of disemboweled or missing limbs, the awful smells of the battlefield, or other horrible experiences that come from battles. In the third section, the Brigade is described as riding "boldly." In the fourth part, the word "Flashed" is repeated; both of these choices seem to glorify the actions of the Brigade, focusing on their heroism and bravery rather than the horrifying reality of war.
In part five, we learn that "horse and hero fell," and part six refers directly to these heroes's unfading "glory." We are instructed to "Honour" their charge and to "Honour" the men themselves. They are, ultimately, called "Noble." Imperatives like these draw attention only to the honor these men have accrued with their brave actions. Seeing only this side of war masks, however unintentionally, the bloody and bitter truth of battle.