I visited Macao during the cold month of December. Suffice to say that I managed to visit all properties inscribed as its historic monuments. I stayed here for two days without being bored at all.
I agree to Ivan's assessment that Macao is largely a misinterpreted site. Beyond the picturesque Ruinas da Sao Paolo, not many tourists get to see the bigger picture that Macao offers (personally, I enjoyed a lot visiting these sites: Largo do Senado, Casa Mandarin, Lilau Square, A Ma Temple, and the Protestant Cemetery compound). Nevertheless, Macao's blend of the East and the West can best be seen through the various religious edifices it has - it is interesting how one Buddhist temple sits side by side a Christian church(in ruins).
Though Macao's monuments are at some distance to each other (the Guia Hill being the farthest), I still found going around Macao to be a very refreshing experience. For one, each of the monuments is truly a representative of unique cultural and historical testaments; thus, overlaps of values represented by each are hardly present. Secondly, the government has to be commended for doing an excellent (and colorful) job towards preserving their enduring gems. One can definitely see the tough dedication being forwarded there. However, I also noticed that there seemed to be an imminent problem that the sites will face in the next few years with their seemingly weak buffer zones and lack of proper urban planning and traffic management. Macao, after all, is rapidly growing, and I've yet to see how the government is looking at the preservation of the aesthetic values of the sites amidst modern, high-rise edifices and installations around them.
By in large, the monuments of Macao are indeed interesting. There is also another site there that is not inscribed -- though it is deemed to be of high cultural importance for Macanese. This happens to be Rua da Felicidade, a little street that may also be worthy for some attention by tourists visiting the city. I also found my visit to the Santa Casa da Misericordia Museum (its entrance is on the right side of the building) memorable as it is one place where one can see religious artworks as a result to the blending of two cultures and their respective marks of craftsmanship.
Offhand comment: the colonial buildings surrounding Largo do Senado reminded me a lot of the buildings within Escolta in Manila - I can just imagine how it would be like if Manila also takes the effort of conserving and reviving its architectural treasures.