As u can see this lens gives a pretty dramatic look to buildings and architectures.
To me, the extreme wideness allows me to take handheld pictures at extremely slow shutter speed, i've even managed to get a clear shot at 0.3s shutter speed.
In short, anyone looking to get a UWA should definitely consider this lens, it's far more formidable than i thought and to me, it made my trip much more worthwhile with it's 8mm
Yes there can be a difference. Rear mounted filters for ultrawide or fisheye lenses are usually designed as part of the optical path, so there has to be a filter in place at all times. May be a challenge if you need to use a GND.
Rear mount? Huge problems. Practical ones during usage, naturally.
Imagine if you're shooting in the sea, with the waves all around you, and you're supposed to mount a ND filter + GND... And your next move is to unmount the lens... And a big wave comes... And then...
Getting splashed on the front element/exterior is a lot less hazardous. Not to mention, if you use strong ND filters like the ND110 and ND106, even with today's excellent live view implementations "boosting" the image, I suspect you will have problems at sunset timing/twilight timing.