Many of you have raised some interesting and very valid points. As a WW2 historian for over 35 years - and one who reads and speaks Russian (poorly but with great determination) - the opening up the Russian achieves in 1991 caused major re-writes in how we understood the Eastern front.
1) Glanzt, despite anyone's opinion, is recoginized as the one of the foremost living authories on the WW2 Eastern front in North America. He's challenged and caused many theories to be re-written in the last 20 years and open new insight in that area.
2) As with any historian, Glanzt has developed his POV and sometimes it blinds him to other views on a subject. This is the single most common failing of any historian, and, IMO, most human being. A gentleman earlier in this discussion pointed this out and he's right on target.
3) Beevor doesn't have the same body of work or primary research that Glanzt has yet. And he hasn't added the same new insights that Glanzt has added to the Eastern Front debate. He's a creditable source, but simply doesn't have the same stature that Glanzt has yet.
4) On Mars, we will never "know" the answer. Too many records either aren't avaliable, or have been altered. But based on the operational planning records that have been released, we know the following about the operation:
a) It was originally planned to jump off 30 days before the Uranus operation. Due to logistics delays, it actually jumped off two days AFTER the Uranus operation.
b) It was to consist of approximately 1.5 to 1.8 million troops - counting reserves - in the offense. The defensive battles at Stalingrad, combat losses, and logistic strains kept reducing this number. The final offense resulted in approximately 500,000 to 600,000 troops - and very few if any reserves were committed.
c) The 30 day delay in the start date resulted in the offense taking place in terrible weather conditions, creating an inability of to supply the troops, and no break out occured.
d) The entire Soviet front suffered from a sever heavy artillery ammo shortage during this period - and ammo was diverted constantly from one part of the front to Stalingrad and, later Uranus as it become successful, from other parts of the front.
So, based on this information, you can literally make a case that both Glanzt and Beevor are both right. Glanzt because the operation was originally plan as a major offensive; Beevor because operationally, the Soviets simply couldn't execute two major offensives of this scale at the same time. Or, that both are wrong depending on how you want to picture it.
And, as another gentleman pointed out, you need to read multiple POVs to get a good grasp of what happening - and different, creditable POVs are best. Most of want to believe that history not subject to differences of opinion and its black and white - unfortantely, most history is more in the shades of gray. So I would recommend taking as many views as possible and measuring them against each other - it's usually interesting at the same time.