At first I was disappointed, then I was frustrated, but now I have to admit, this isn't a bad game at all.
Oh wait. It IS. Sure, it has some flaws. Traffic being the most notable, making bus lines very difficult to profit from, and tram rails need to be laid OFF the streets to be useful. The game devs themselves admit traffic isn't working entirely as intended, and they're working on a patch. In the meantime there's a couple game-file tweaks you can make (see the official forums) to lessen traffic density until that patch is out. It does NOT make the game unplayable. After 5 attempts at the first scenario, it gradually dawned on me that I wasn't getting traffic-screwed, I was just failing the game. Then I learned to use the metro, beat the scenario, and went on to beat the next two on the first try each. The key seems to be using a metro for a backbone, tram lines leading away from the metro stops, and bus lines out from there to the outskirts (where there's no traffic).
Overall, I have to say I'm impressed. This game may not have the depth (and scope) of OpenTTD or Railroad Tycoon 3, but it's still quite fun to play, and the graphics and soundtrack both being beautiful don't hurt either.
Oh, and the 4-city limit? Turns out there's a map editor. So yeah.