I've used Russell's Dri-Power t-shirts for a few years now but was limited to the standard XXL found at my local sporting goods store.  Being a fairly big guy (6'5", wear a 48 Extra-Long jacket), these barely reached the top of my shorts so were relegated to workout undershirt status.  I was excited to try the same shirt in a "Tall" version since all my other standard shirts (EddieBauer, Gap, etc) are XXL Tall.  Simply put, this shirt is monstrous.  The length of the body is a good 8" longer than my standard Russell's and the cut of the shirt is clearly much more generous despite being the same size.  I have a XXXXL shirt from college that I got as a joke and this Russell XXL "Tall" is cut similarly (way off the shoulders, excessively wide sleeves, and roomy enough to stuff a pillow or two).  The standard XXL fits the body perfectly, just isn't long enough in the body or sleeves.  Tall's generally only add and inch or two in the body and sleeve to the standard size so I have to give this product a below average rating.

Aside from the sizing, I do love the performance of the Russell Dri-Power t-shirts.  They are definitely a good value, even if just for an under-layer.