I have a Samsung Galaxy S II, I wouldn;t be without it....my partner has an Iphone but I wouldn't give you a thank you for it....
I pay £27 a month to O2 and have unlimited texts and pretty much unlimited web....
Mines £8.32 on Virgin (depends on phone you choose, that's the lowest amount). I get 100 free mins to UK landlines / mobiles and 100 free texts. You pay for internet 30p for each day that you access it no matter how long you access it for or how many times. I mainly got it as it meant I could use the free minutes instead of paying for calls made on my landline.