I like the expansion tiles. It almost feels as though they were left off so as to be made available as promotional offerings. They should have been in the original game, or at least made readily available.
Played once with 5p. A very nice expansion. I liked everything about it, except that the last 1 or 2 (of 15) master builders to get placed often had nowhere useful to go. Perhaps that's just part of the design. Whoever places the first master builder also plays the very last one.