Just finished Big Ben. I am of two minds on the set.
First off, it is both larger and smaller than I imagined it being. It is hard to explain, but it is so much more compact than I originally thought, yet still towers over many other sets at the same time.
There are a lot of really, really awesome techniques throughout the build, as is expected with a Jamie Berard set. Totally called the main tower being certain bricks turned sideways, but totally didn't call how they attached to the main body. It is done in such a stupid simple way that it is brilliant.
The way the clock hands move is a lot simpler than I imagined, which impresses me, while also not as complex as I expected, which disappoints me. The good news is that it is not something that you can screw up so bad that it cannot be easily fixed, so there really is no pressure when it comes to that part.
As for the rest of it, this set is an OCD nightmare. A vast majority of the detailing on the set is done using 1x1 tiles and bricks, thus aligning everything can be a challenge if you want this exact. This is particularly troublesome as a big part of the set is using 1x1 areas turned at angles on single studs, and then stacked on top of that. So if the bottom layer isn't perfect, the rest won't look as good.
On the other hand, this type of building allows for some very cool textures and looks to the set that cannot be achieved otherwise.
The other criticism/praise for the set is the extreme repetitive nature of the build. While the repetition gets boring after a bit (particularly the 2x build for the middle part of the tower), it is the only way to really achieve the look of the set. The ends justify the means.
And holy parts pack! If Tower Bridge was an insane parts pack for pieces, this jumps right by its side. The main thing this gets you is lots of smaller, detail oriented pieces and in large quantities. You will probably never want 1x1 dark trans bricks again after this set.
In the end, This is highly recommended. Even if the monotony of the build wears on you a bit, the gorgeous display piece it yields is totally worth the price. It really is one of the most striking sets I have built in the last several years.
