I own both the 640 and the 640 XL and I'm still deciding which one, if any, to keep. The 640 XL is fun to mess around with, it's very nice for searching the web and watching videos and I would guess for playing games (though I'm not a gamer at all), but to have it as your (well, my) main phone seems a bit cumbersome so far after about a week and a half or so, you just know it's there all the time when it's on your body. The 640 seems like a really good compromise plus it's easier to use one handed and front pocket-able. The 640 XL fits in the front pocket of all my jeans and pants but I'm much more aware of it and nervous that I'll bend it when sitting down with it in there.
The build quality for both phones is very good, they don't feel or look cheap at all. The 720p screen are very nice and the 640 XL has True Black technology (the 640 has a lesser True Black version implemented, but still looks fine). To my wife and I the 640 XL's screen looks a tad better, clearer, maybe sharper, just a little better. You would think the because the 640 is packed with my pixels it would look like the better display. That being said the difference is minor even when compared side by side. The whites look better on the 640 XL for sure, they are much whiter than the 640 which are "dingy" in side by side comparison, but again you'll likely not notice it using the 640 on it's own.
There is relatively minor but noticeable scrolling lag when web browsing on both phones on many sites, this is my main gripe and I'm trying to get past it, still not sure if I can. Compared to Android it often takes more steps/taps to accomplish tasks, though I'm told W10 update will change some of this.
I like the look and feel of Windows Phone. I'm not a big third party app guy and I understand coming over from Android it will take some time to find my way around, so I'm giving it some time. That being said, I'm not sure the 640 XL is for me, the thought of a phablet might have been better than the reality for me, just not sure I have much use for such a big phone. In fact before I turned to Windows Phone I was considering the first generation Moto X with it's 4.7" screen and very small overall footprint.. and I'm still considering it as I'm finding I like the idea of my phone just being in my pocket.. just there when I need it, but not something I have to think too about much. We shall see!
The build quality for both phones is very good, they don't feel or look cheap at all. The 720p screen are very nice and the 640 XL has True Black technology (the 640 has a lesser True Black version implemented, but still looks fine). To my wife and I the 640 XL's screen looks a tad better, clearer, maybe sharper, just a little better. You would think the because the 640 is packed with my pixels it would look like the better display. That being said the difference is minor even when compared side by side. The whites look better on the 640 XL for sure, they are much whiter than the 640 which are "dingy" in side by side comparison, but again you'll likely not notice it using the 640 on it's own.
There is relatively minor but noticeable scrolling lag when web browsing on both phones on many sites, this is my main gripe and I'm trying to get past it, still not sure if I can. Compared to Android it often takes more steps/taps to accomplish tasks, though I'm told W10 update will change some of this.
I like the look and feel of Windows Phone. I'm not a big third party app guy and I understand coming over from Android it will take some time to find my way around, so I'm giving it some time. That being said, I'm not sure the 640 XL is for me, the thought of a phablet might have been better than the reality for me, just not sure I have much use for such a big phone. In fact before I turned to Windows Phone I was considering the first generation Moto X with it's 4.7" screen and very small overall footprint.. and I'm still considering it as I'm finding I like the idea of my phone just being in my pocket.. just there when I need it, but not something I have to think too about much. We shall see!
just put a nice screen protector on it . And if you like , you can add a case as well. 
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