So I had a Blu WinHD (Non-LTE) a few months ago and returned it. I've now had the 640 for almost a week - since they're in the same general $ range, here's a few comparison notes (Note that I returned the WinHD because I didn't like it)
1. Glance. I went from an 810 to the HD and man did I miss glance, and especially double tap to wake. Honestly, I may have considered a decent Android, but these 2 things are what are keeping me hardcore in WP.
2. Performance. Apps were far more laggy and crashed far more often on the WinHD. I've had a bit of that on the 640, but not much at all.
3. Bluetooth. Neither performs great streaming to my old Moto T505 (BT 2.0 with A2DP) with dropouts. The Lumia 810 was better than both - but I probably need to just get a new BT Device with FM Capabilities)
4. Buttons. The WP8.1 screenshot changed to power and volume up, on the WinHD they were in the same place on opposite sides of the phone - the top corner. I was deleting a screen shot every time I took the phone out of my pocket.
5. Camera. The WinHD camera was terrible. The end.
6. Construction. Both devices feel sturdy and well made. The click back on the WinHD was probably preferable, thought it did make changing the color impossible, as the sides would still have been white, even with an orange or yellow back.
7. Phone. I don't know, I never take calls on either
8. Physical Buttons. The Win HD did have the windows/cortana/back buttons on the screen. That was my personal preference.
9. Dual Sim. I have the TMo single sim variant, and that's plenty for me. The dual sim just annoyed me as I'd be texting on no sim and have to go back and change, etc.
10. LTE. Don't buy the non-LTE variant of the WinHD, or any phone, really.
I don't remember the screen on the WinHD well, but I didn't have any issues with it, so I'm willing to say they're even there.
Overall, the Lumia 640 is a better phone, and depending on sales and such, probably cheaper. The clear winner for me.
1. Glance. I went from an 810 to the HD and man did I miss glance, and especially double tap to wake. Honestly, I may have considered a decent Android, but these 2 things are what are keeping me hardcore in WP.
2. Performance. Apps were far more laggy and crashed far more often on the WinHD. I've had a bit of that on the 640, but not much at all.
3. Bluetooth. Neither performs great streaming to my old Moto T505 (BT 2.0 with A2DP) with dropouts. The Lumia 810 was better than both - but I probably need to just get a new BT Device with FM Capabilities)
4. Buttons. The WP8.1 screenshot changed to power and volume up, on the WinHD they were in the same place on opposite sides of the phone - the top corner. I was deleting a screen shot every time I took the phone out of my pocket.
5. Camera. The WinHD camera was terrible. The end.
6. Construction. Both devices feel sturdy and well made. The click back on the WinHD was probably preferable, thought it did make changing the color impossible, as the sides would still have been white, even with an orange or yellow back.
7. Phone. I don't know, I never take calls on either
8. Physical Buttons. The Win HD did have the windows/cortana/back buttons on the screen. That was my personal preference.
9. Dual Sim. I have the TMo single sim variant, and that's plenty for me. The dual sim just annoyed me as I'd be texting on no sim and have to go back and change, etc.
10. LTE. Don't buy the non-LTE variant of the WinHD, or any phone, really.
I don't remember the screen on the WinHD well, but I didn't have any issues with it, so I'm willing to say they're even there.
Overall, the Lumia 640 is a better phone, and depending on sales and such, probably cheaper. The clear winner for me.