"This is a great set as many reviewers said. I'm not repeating here.
Here're some suggestions:
1) The carriers are too small to fit mini figures. Girls with long hair cannot do front facing because of their head / hairs will be blocked by the 2x1 just under the top cover. Mini figures (boys or girls) need to adjust their hands in a un-nature way to fit the side facing. Please see the pictures for details.
2) The carriers are too close to the base. If only one figure sits on a side in a carrier, it will hit the base slightly because of the uneven weight. The doors of carrier needed to be closed very well to avoid hitting too. How about making the wheel smaller and give more rooms to the carriers?
3) The single instruction book looks cool but make it hard for sharing. I like playing LEGO with family and kids. The manual could be better if it could be written with more parallelism. It's important for sets with a lot of repetitions like this. It would be very fun if the small kids could help building the carriers a the same time while I'm building the base.
Nevertheless, it's a great set with no doubt. I had a lot of funs in building it. :)
The comments above just hope to make the LEGO to be a greater product."