HTC One performance vs S3

Hi All,

I currently have a Galaxy S3 (International model) and I am now due an upgrade. My network operator has offered me a good 12 month contract on the HTC One, which actually works out cheaper than the Nexus 5 would on a 12 month SIM only plan.

12 month works well for me at the moment as there isn't really a handset I would want for 24 months at the moment, and I suspect an iPhone with a larger screen may appear late next year.

I am seriously tempted to go for the HTC One but was wondering, how much of a step up in performance is the HTC One over the S3? Is it a much more powerful handset?

Is it worth upgrading or should I try and make the S3 last another year?