I just finished building 75054 last night ( the latest AT AT Walker) to hit the shelves. While I like the head on this new one…I still think that 4483 is the better build of these 2. I actually took set 8129, (the previous version of the AT AT), apart and used it to build another 4483 version, but in the new BLEY colors. Yes, I like set 4483 that much. Or maybe it was I did not like 8129 enough to keep it the way it came. (My BLEY version of 4483 is what you see in the photos). The new version (75054) is really very weak on play value. The original 4483 has removable side troop seating, and the speeder bike cargo area to launch from the back. I think the only thing going for 8129 was the minifigs / Han Solo Bespin minifig honestly (the only one to date). And yes, I did not mention the motorized AT AT for a reason…although it should be included as we have 4 AT-AT sets officially.

Head on shot:

Back view:

Side compartment on the new AT AT…no interior, just a lame trap door with no cable line or anything. Watch your legs on that landing. At least it's Hoth, and not Endor.

4483 Side compartment…oh yeah, we got stuff going on in there!

Aft side shot of the new AT AT…just technic, frames and support structure going on,….blah.

and a shot of the 4483 ,same area….but with a snowie on the bike ready to hit it! When you pick up the two models you can feel the difference in the weight for sure. Again, I think the head on the newer one is better, stays together better / more sleek, and 4483's head has some issues ( staying closed and attached) being two of my gripes on that one. As a matter of fact, when I picked up 4483 to put him back in my case his head fell off, again.

Curious as to everyone else's thoughts, now that we have 4 to compare!
Comments
Nice to see you in the hood :-) This place is as addictive as Lego, watch out.
#4483 - The size of the model is great (the largest of the four) and I like the Speeder Bike hold in the back, just as it is situated in the film. However, the head is awful due to its fragility, the colour scheme is some way off as there is too much dark grey and the shape of the main body section is not particularly accurate. It was a good set for 2003 but beside the more modern versions the issues with it are all too clear in my opinion.
#10178 - Of course the main draw to this set is the fact that it is motorised, which is brilliant. The function works well and it is a lot of fun to play with. However the body is far too shallow in height, and the placement of the head and legs are not ideal to facilitate the walking feature.
#8129 - This set is far more accurate than either of the previous two, but at the cost of size. It is a decent model, but not really big enough to feel truly intimidating (for a Minifigure) and some areas of the armour plating are a bit fragile.
#75054 - The legs are far longer relative to the body than on any other model, which is accurate to the film as they look fairly spindly, as they should. The entire model is very sturdy and the shape is perfect. The main issue with this set is the price I think, although if you are looking for an AT-AT today this should be it as it is as expensive as any of the previous models are on the aftermarket.
Just my opinion, but I would rank the new model at the top. Even though it is a bit tricky to compare it to the motorised version as that set is all about the functions rather than the appearance, I still favour #75054 overall.
Don't get me started on #10178 I've always thought that was a hideous beast and no amount of clunky walking can ever make up for it.
#4483 is without doubt quite fragile but as mine are only on display it doesn't bother me too much.
Perhaps a bit of a combination of the oldest and newest would yield a near perfect one at this scale. #75054's neck is much better and so is the engine thingy near its bum.
Just my thoughts.
i'd like to get one of the new model heads and put it on the original. that'd make me happy!
i missed out on the motorised one. i might try and bricklink it at some point, but not urgent and i'll probably get the new one and snowspeeder in the sale...