Like many others here, I've really been looking forward to CitiesXL, but now I'm very disappointed that we'll have to pay a monthly subscription just to play a less-than-dumbed-down version of the game.
When I spend $40 for a game, I expect a game that is complete ... not one where some of the content is left out (just to force people to pay more).
I understand that there are features that would only work online (such as trading with other players), but this just isn't worth the subscription costs for many of us. And in too many ways the single player game has less actual content than what SimCity4 gave us. I'm totally bummed out that MC's decision to focus so heavily on the multi-player-subscription aspect is in all likelihood going to kill this game (unless they lower their rates to something reasonable). And that means that we will have to wait for years for a true SimCity 5 (if we ever see it).
In my opinion, MC would have been much better off raising the price on the game, while including the first 6 months online subscription as free.