If it's China, of course, the investment may prove worth it. There is much to be said for the branding impact of cool technology: I, for one, was eager to board the maglev the moment I heard about it, and the ride helped jolt me out of my preconception of China as a land of sock-and-toy factories. Also, China is now the proud parent of a "National Research and Development Center for Maglev Transportation Technology," which presumably builds on know-how that was once the property of Transrapid.
If it's Transrapid, the company now has a live demonstration model with which to try to sell real intercity systems. But one reason Transrapid handed China the keys to its technology kingdom, presumably, was to earn the pole position in the bidding for a planned Shanghai-Beijing maglev. But alas, China dropped that plan—the Beijing-Shanghai maglev would have cost almost $50 billion, three times as much as a traditional fast train—while keeping the snazzy technology. So, it's not clear how much Transrapid really got out of the deal.
The Pudong line may eventually turn out to be a decent deal for airport users. If Shanghai keeps expanding at its present rate, traffic will soon clog the airport highway and choke off the taxi option, and the maglev terminal will soon be in the heart of the city.