Should I upgrade to an Iphone4 or new Nokia E7 ?

[chanceadancer]

Friends and family so I can upgrade for 50% on Tmobile to IPhone4 for free, and get unlimited minutes/texts for £35/month.

Or I wait 2 months, and probably pay £100 for upgrade and stay on same tariff- £17.50 for 750 minutes.

Any ideas???????