Major problem with Legos: just like puzzles what do you do with them when completed? You put them on a shelf and they collect lots of dust.
My children got into them and then we found a whole room had them all over the place. The worst part: all that plastic began off gassing this horrible and dangerous smell, really noticeable on humid days in particular. We have been cured of further building and collecting and feel healthier as a result, lol.
Contacted Lego and they said they are trying to find a more nontoxic formula. Wish they still made them out of wood.