Lets talk about the MicroSD first
Like everyone I love to have a phone with MicroSD feature. It makes it easier to swap between my phones as well as to transfer data to my PC. I myself won't mind spending lots of money on a fast microSD card but I have yet to find one that is both FAST and LARGE in capacity. On my Note 4, i'm using Sandisk Extreme and my fastest bench mark test was 70mb Read and 39 Write. Now these numbers are decent but In my opinion MicroSD cards are not keeping up with the speed of phones these days which is cause bottleneck issue and is one of the reasons behind all the lag that people complain about.
Now with the Universal Flash Storage (UFS) 2.0 which has 350Mb/s Read and 150Mb/s, you can rest assure it will not cause any lag from viewing pictures and videos as well as swapping from app to app. Not to mention you can always plug in your OTG cable with flash usb and do all your backups there titanium backup or simply copying your data there which is what i'm doing currently.

Samsung has ultra fast 128GB UFS 2.0 ready for smartphones
As for the Battery,
While having a removable battery is a plus, from my personal experience I have yet to use it when I want too. I have extra battery and charger for my Note 4 but i always find my self plugging it in rather than taking the cover off and restart my phone. Now with all the new features to charge wirelessily and fastcharge 2.0, I don't think anyone would have any issue. Iphone users as well as other brands from nexus 5,6 and htc didn't complain about their battery then why should we when are ahead of the game in many ways?
With all the features we are getting on the GS6, I think i can easily sacrifice on these too.
Like everyone I love to have a phone with MicroSD feature. It makes it easier to swap between my phones as well as to transfer data to my PC. I myself won't mind spending lots of money on a fast microSD card but I have yet to find one that is both FAST and LARGE in capacity. On my Note 4, i'm using Sandisk Extreme and my fastest bench mark test was 70mb Read and 39 Write. Now these numbers are decent but In my opinion MicroSD cards are not keeping up with the speed of phones these days which is cause bottleneck issue and is one of the reasons behind all the lag that people complain about.
Now with the Universal Flash Storage (UFS) 2.0 which has 350Mb/s Read and 150Mb/s, you can rest assure it will not cause any lag from viewing pictures and videos as well as swapping from app to app. Not to mention you can always plug in your OTG cable with flash usb and do all your backups there titanium backup or simply copying your data there which is what i'm doing currently.

Samsung has ultra fast 128GB UFS 2.0 ready for smartphones
As for the Battery,
While having a removable battery is a plus, from my personal experience I have yet to use it when I want too. I have extra battery and charger for my Note 4 but i always find my self plugging it in rather than taking the cover off and restart my phone. Now with all the new features to charge wirelessily and fastcharge 2.0, I don't think anyone would have any issue. Iphone users as well as other brands from nexus 5,6 and htc didn't complain about their battery then why should we when are ahead of the game in many ways?
With all the features we are getting on the GS6, I think i can easily sacrifice on these too.