Just a word of warning, I've found it very hard to move from an iphone to Android. Admittedly I have a fairly crap Samsung Ace but I'm going back to Apple as soon as I possibly can. I'm sure Android is great but if you've ever had an iphone, it's a tough move to make!
I have the android ww app (it's the German one, I'm not sure the UK version is out?) but it's really not very good. The thing that really irritates me is that the decimal point on the calculator doesn't work so I have to round up and down and I don't think that's particularly accurate. The other thing applies to most Android apps - they aren't designed for a specific screen size so they don't always appear properly. On the ww app, the text spills out of the buttons because the text isn't scaled down to fit the screen in the same way that the buttons etc. are. It has improved slightly with updates but it drives me crazy especially as the iphone app is so much better.
/rant.