I've owned a G5 (three actually, one for me and two for my wife) since launch and love it. It's lightning fast, has a fast and accurate fingerprint sensor, great camera, and charges ridiculously fast too.
Cons-
The battery life isn't quite as good as other current flagship phones, but I've largely remedied that with my own screen brightness program. The stock auto-adjust is almost twice as bright as you'd need at nearly all times when indoors.
Also, the screen isn't quite as nice as an iPhone or Samsung. Most people can't even tell but I'm a stickler. It has a noticeably cool color hue and the contrast is only OK, making whites slightly bluish and blacks slightly grayish when compared to the other screens. If I'm being super analytical, I can also see a slight light bleed at the edges on an all black screen (only on mine, my wife's has none).
But hey, I can swap my battery!
That's something none of the other flagship phones can do anymore. I don't break my phones much so I only really upgrade them when they're slow. Because of that, replacing the battery when it loses its full capacity instead of having to replace the whole phone is a big plus for me. Also, the excellent charging speed makes it not much of an issue, and the fact that my phone is never on a cord to charge is also a big positive. I only charge batteries, when my phone is low, I simply swap the battery instead of plugging it in.
As for the screen, it's still very vivid, bright, crisp, and responsive. It's the easiest to use outside that I've ever owned.
Also, you'll pay nearly half what a Samsung or iPhone costs and it's just as capable. I'm very happy with it. Most won't even notice the shortcomings I've listed, I'm a rather ANALytical guy when it comes to comparing stuff... lol