I'm nearing completion on mine and I was wondering if you plan to use the GI figures. I'm guessing no, by the scheme you chose and the clothing the figures are wearing. I can't tell, but it appears you left the "handles" Tamiya provided attached. They are the solid strips along the center of the engine vents on the rear deck, and the handles on the loader's, driver's, and assistant driver's hatches. I recommend replacing them with wire in the future. The pack on the front looks too shiny for the dust appearance. The .50 cal bolt charger (the piece sticking out on the right side) and the handles should be wood. The 2" mortar tube should be drilled out a bit to give it more than a "dint in the turret" appearance. In the future you may want to add a little more detail to the rear turret in respect to the .50 cal stowage. On the barrel stowage brackets (the two 45 degree pieces on the rear) there should be a piece looking a lot like the top of the bracket in front and to the left of the commander's cupola. There should also be a bracket for the cooling jacket cradle for the gun, but Tamiya left this out. It can be found on the more extensive PE sets. Tamiya had some very fine detailed parts in places and in others - well - plugh. For instance the .50 cal barrel holding bracket on the top mentioned above is finely molded (though a bit too thick), yet I have no clue as to where Tamiya got the idea to mold the horn the way they did! Also, the searchlight seems to be backwards. I believe the light should be on the right of the post and not the left. However, from photos I think it could be mounted either way. A drilled out drainage hole on the splash rings for the fuelcaps should round out things.
Now that the bad is done, the good. Though a shorter list than above, the items mentioned far outweigh the deficiencies (most of which were the manufactuers fault and not yours). The weathering: supurb. I can only hope to emulate the dusting effect on the sides. The helmet on the .50 cal stowage is an interesting touch. The ropes and knots are well done. I like that you put a star on the front and then covered it up with stuff; it gives a true since of realism with things appearing to be added over a duration. Also the star on part of the ammo ejection port is a very cool touch and, at least for me, wouldn't be an easy task to do without errors. My only recommendation for the next sherman in respect to the star would be to extensively fade and "paint" over it as they stood out as a "star" target for german gunners.
Excellent job