it sometimes shows some taxis, most of the time it doesn't…

currently showing just a feew (2-3) cabs in london which probably is incorrect (like kevingibbon also noted).

apart from that it's slightly annoying you start zoomed at some street level when you pick a city (in my case london as that appears to be the only one having data…). if you're exposing your own location it would make sense to zoom in at street level, but if you're not i think an overview of the selected city would make more sense