I chose to buy this set because I wanted a challenge. When building this set, you have to get through a lot of challenges just to put it together. I liked the fact that even though this set was huge, it had an alternative model which was surprising seeing how big this set actually is. I thought the bucket wheel was a great detail since making something like it would normally end up looking like a mess, but the LEGO group pulled it together and made it look and work perfectly. But when it comes to the disassembly, this set is a pain. It's all fine until you reach the base. This will be the most difficult part of the disassembly. Unless you have small fingers, you will not be able to pull out the pegs and axles inside the base, leaving you with a mess.

3996 Parts, plus some spares, so it is a huge amount of parts, most of them straight forward and no fancy colors, even if there are a lot. You have lots of liftarms, pins, panels and gears. Also chains you have lots and lots.

In total you build in 8 sections, that is quite good, because so have not too many parts to sift through.

The only thing, in my opinion, is, that this whole massive machine is powerd by a lonely XL-Motor. So you have a long transmission to everywhere you need to set something in motion. The bucket wheel it self is powered by one of the conveyer belts.

The functions are plenty, 2 conveyer belts, the bucket wheel, one belt can be turned by 180 degrees, it is moving itself on chains, but only straight. You have a extra vehicle that takes the load. Also a lot of details are there.

The downside: to less power, Lego should have put at least 2 motors in, and an RC. The bucket wheel gets easy blocked, because something clogs one of the conveyers, so you have to look around and remove the blockade. So the conveyer belts should have been a bit more protected against spilling over.

The instruction has also one or two errors where something was missed in a step. So I looked o n the pages before, just double check myself.

But in general it is a good value set, you get tons of parts, you can play nicely with it - just keep a eye on the conveyers - and you have some powerfunctions. My kids are loving it, just because it is sooooo big. Hard to find a place for it ;)

In my opinion this set should have been the anniversary model from last year, just with at least one or two motors more. Instead we got the infuriating 42070.

The whopping massive count of pieces which sets me and my friend's jaws apart when we open this giant box of 42055.

I had this built alongside with my friends, taking turns and took us almost 9 hours (with breaks in between) to complete this set.

Nonetheless, while we were taking our sweet and bitter time (slightest mistakes and you are in trouble for redo) for this set, we does achieve great satisfaction far more than we expected after the set was complete, its size is monstrous and intimidate, and of course, it works wonder.

Appearance
Although this LEGO bucket wheel excavator does not resembles any of the real life bwe, the design is still impressive, some might say this set looks rather crude, but you gotta forgive the ugly chassis it presents, is functionality before looks, and the dark blue and yellow color does blend quite well together in overall looks.

This set is sturdy and solid built, capable to withstand rough handling, easy to carry despite of its size, and not to mention how many attention you will get if you display this on your working desk.

Functions
Having only ONE motor to move this giant piece of lego (weighted around 3kg) is a huge disappointment for this set, its moves and works like a snail, and I do understand that this was suppose to move slow equal for its real life counterpart, but seriously it could work just a little faster, eg. the superstructure rotation.

I suggest replace two of the clutch gears attached on the motor (near the battery box) with gear wheel Z24 so that it can moves a little faster on a pleasant speed, although you need to switch on the function first before you turn on the power to prevent the motor from being stalled. It is a nice try and it does really sped up all of the motorized functions to an impressive speed than using the clutch gear.

Lets not forget about the dump truck that comes with it, I personally do love this small white dump truck because its steer so smoothly without any backlash and does its job super well done with simple operation.

The building of this set is pretty straight forward, friendly enough for beginner whom just step into technic series, and the huge amount of parts is definitely worth the bucks.

Other reviewers have already done some great and detailed reviews, but just to add a few additional points:

1. The build is absolutely amazing!! The vast majority of Technic sets are cars or trucks, there are a few aircraft and the odd motorcycle. This model rather builds like a building, with a solid structural frame, and lots of unusual and interesting techniques used. It's a tough but very rewarding build.

2. The parts selection is awesome! Not only is this set huge, but it has heaps of big liftarms (85 of the 15-length ones), Technic frames (60+), around 150 gears and a number of panels. The included power functions and wheels and steering in the small truck add extra possibilities for your own creations. In other words, if you only ever bought one Technic set, you wouldn't go wrong with this one.

3. Regarding the difficulties some have reported with the functioning of the set, my experience has been the opposite - I've found the model to be powerful and robust, able to dig up heaps of bricks while bumping up against my hands and the ground, without a single click from the friction gears. What I did find was that, even more than usual for a big Technic set, you need to keep checking back to ensure that gears and axles can spin freely, and wiggle them loose if they don't. Some of this construction has a number of gears sandwiched between liftarms, and a lot of friction can result if you don't loosen them constantly while building.

Finally, this set passed the 8-year-old test. My daughter absolutely loves how it works, more than any other set. It's huge, looks great and works in a really fun way. I'd recommend it highly.

In this video you can see how you can use the transport mechanism to film individual pieces and recognise them with AI
https://www.youtube.com/watch?v=Uv8izH_soQQ