Hmmm can't say I'm too impressed of what was revealed. I don't feel like it's a real significant upgrade over what the s4 already offers, just as what many s3 owners said about the s4.
At this point, and I've been saying it for well over a year now, this proves to me that hardware has hit a plateau. The fingerprint scanner, I see it not really being used to its full potential (use with PayPal and such), but simply as another way to unlock the screen. The heart rate monitor, I like this addition, but I don't think it'll be used as often as Samsung hopes it will be. These two are cool features, but they're novelties, again just my opinion.
One thing that does impress me is the camera and its new software which I hope makes it to the s4 through an update (unless it's limited by new hardware in the camera).
I've only skimmed a few articles and watched a handful of first impression videos, but I do look forward to an in-depth review in the future. However, when it comes to actually wanting to upgrade, it would be a pass for me right now.