Imo, this is the worst GB. The reason why I rank it lower than the Colosseum and Notre Dame is that it cost a bunch of ME goods, and the other two GBs are above par in their age on it's first few levels, while you need to bring this GB above level 8 to bring more happiness/space than an unpolished Drive-In Theater.
The only reason I would build this would be for aesthetics or if I wanted to build all GBs for the fun of it.
I built 0ne just BC i had extra space and the goods but my guild took a liking to it and within a week it was level 4 already. It is currently level 5 with donations slowing down pretty fast. I think its defiantly not worth the space but without a doubt a really awesome looking GB. it fits pretty well next to Automium.
On Cirgard I was one of the first players to get a Space Needle, so it's gotten up to level 9 and is ok for happiness, just too much investment for the amount of reward. After building it on one server, it taught me not to bother with building it on another. If you're going to invest in a happiness/coins building lotus is a better use of the city space.