There seems to be a lot of wrong information here.
1. I have not had this experience except with updates, does this happen when downloading files through a web browser?
2. Pocket File Manager is a good file explorer and there are many other good choices. The file managers seem to be able to do a lot more now then when I came to Windows Phone.
3. I haven't experienced this, but I believe you on this one.
4. This is somewhat annoying to me, but I don't take a lot of pictures.
5. Yes you can, just need an app. I use "Unit Converter" which is disguised as a unit conversion app but lets you hide and encrypt pictures and videos.
6. There are a lot of third party apps available and have met most of my needs. I wish some Google Apps were available that I used when I was on Android (mainly Google Voice and Chromecast support).
7. Put a lock code on your screen? This is the case for Android and iOS as well. I know there are apps on Android where you can set passwords for different apps, but who really needs that.
8. I personally really like the WP8.1 update with the notification center. I really missed having a notification center on Android. Battery life is about the same for me.
I have been a long time Android user and I always rooted my phone and flashed ROMS but I have since switched to WP and like it much better than Android. I still switch back to my android phone from time to time to play around with it but I always come back to my WP. I was looking at the 1320, but it did not have the 3G/HSPA+/LTE bands I was looking for. I ended up going with a Lumia 820 because of the micro SD card slot and removable battery. I think only having 16GB of storage and no expandable storage with the Lumia 920 would not be sufficient and is why I did not end up going with one. I would personally go with the 1320 over the 920. In the end it all depends on what you want out of the phone. The bigger screen with better storage or better screen with limited storage. Performance will probably be about the same, but maybe a little better with the 1320's better processor and GPU.
I wrote what I have faced so far. I may be wrong or mis informed. However, honestly speaking, I used all OS except iOS ( But I know little abt it as my brother owns it) that's why I was disappointed after using WP 8. WP8.1 was my last resort and definitely it helped me to change my decision to move back to Android. However, its a fact that even after massive update from Microsoft, WP 8.1 is still behind other OS and Microsoft needs to listen to its users to upgrade and make it best.
1) Yes, try to download big files like Here Maps, Big size games like Asphalt 8 etc. Take today's incident, due to last night heavy rain, my broadband is not working so my WIFI. But my data plan services is working fine. Both are different service provider and I need to update Pocket File Manager, network +, 2048, Line, touch, PDF reader. I have to wait for wifi, no option. Microsoft needs to understand most of the world does not have hi speed wifi around them like in USA people have.
2) I may be wrong but in built file manager seems to work more efficiently then third party as it is the issue of deepest kept file in the system and permission from OS.
3) I am surprised that you haven't heard about one of the most common issue of WP.
4) Phones are for everybody weather he takes less picture or more. Cant segregate on the basis of habits.
5) I may be wrong but I feel WP apps to hide pics does not work efficiently as they don't move files to hidden folder, actually they copy it to hidden folder and after sending pics to that gallery lock, we need to delete it from original and if you want to retrieve it or unlock it, it wont go back to original folder, it goes to "Saved Photos" folder. where already you have many pics saved and you need to search manually for your pics to see. Just imagine if again you want to send it back to lock, again you have to select>send>select>delete from folder.
6) Apps are the key to success of any OS now a days. weather its a big company or small, every body has their app in iOS and Android. But WP just can not compete.
7) Its my humble request that don't take it personal, I am just giving examples. Imagine someone has some very personal pics of his girlfriend or wife in his phone and if your boss's/friend's phone battery gone dry and he asks for your phone to do few calls, in that case one needs to open the security lock. Or take it other way, everybody has at least few restricted picture or videos in their phone, I case your close one asks for phone just to play around with features so that he/she can make up his/her mind for next phone change then....one needs to protect his phone all the time. What I am telling is very practical thing which happens in our daily life. So, that statement " who needs that" is very theoretical not practical.
8) you are lucky that you battery is good. Most of the people are facing battery problem after WP 8.1 update.
As I said, phone is good but Microsoft has to be a bit flexible on few things. And 920 has 32 GB internal memory. 16 GB phone which you were talking about is lumia 925.