Here are the features you find in the iPhone app.
-- Track by flight # -- track one flight at a time, by airline & flight #
-- Track by tail # -- track one flight at a time, by tail #
-- Search by flight route -- get a list of flights between 2 airports
-- View airport activity -- concentrate on one airport, look at Arrivals, Departures, En Route, or Scheduled, one at a time.
-- Nearby - Google map with airplanes in the vicinity of your location. Needs iPhone location service (from GPS or networks). Works very much like the website for real computers, running "airport activity".
Of these, only the "Nearby" function doesn't exist in a real useful way from the mobile version of the website. The closest equivalent on the website is "airport activity", which allows you to focus attention on whatever airport you want, not just your current location.
* Pro: watch flights near any airport in the US;
* Con: only one zoom level, i.e. only one size rectangle around the airport; and no tapping, zooming, or other interaction with the map.
The website opens with a form allowing
-- Track by flight #
-- Track by tail #
-- View airport activity
and a link to a search for flights between 2 airports.
As I said, it doesn't have that "Nearby" map per se, and so far none of the maps seem to be clickable (anything you can interact with). So you can choose an airport and see a map with airplane icons, but you can only look at the map and click on a list of flights to or from that airport. "Nearby" is definitely much better, so if that's the main thing you're looking for, the app is the way to go.
But in addition to those 4 main functions, the website also has buttons for
-- Pilot Resources (airport information, aircraft registration)
-- Aviation Photos
-- Squawks & Headlines
These are not available in the app. The first three are definitely useful for some people. "Discussions" is currently having a bad month or two, but might be pretty sweet after the upgrade. I don't know whether you need the "Contact" page from your mobile device.
So that's why I said the website has more features than the iPhone app. There's only one thing the app has that the website doesn't (yet) have: Nearby. There are several things the website offers that the app doesn't have.
So I strongly recommend you try the website through your Android machine, and see if it meets your needs. Since the app doesn't seem to be coming soon, and probably won't have more than the iPhone version, it's more worthwhile to concentrate on the adequacy of the web interface, which does seem to get occasional updates.