For negative first: the 45mm is not quite as good as the f2 / 30mm unfortunately at full aperture and must be easily dimmed to approximately F2.2 to get even on the edge of a 30mm the appropriate focus. It has been even at maximum aperture slight defects in coloring in some edges that vanish only at about f2.8 aperture. But you can ignore in everyday life thoroughly.
There are for the 45mm no attachable lens hood, but these must be screwed as the pancakes. I have one of JJC for 30mm, which I also use on 45mm. There, the lid of the diaphragm is screwed, so it may be, for transport on the lens in place of the lid remain
But you have to say that there is a critique on a high level, because I had a farmstead on the 30mm pancake like "Pops lens".
Now, the positive part:
The 45mm focused rapidly on the NX300 and is good also for sports and AF-C and AF tracking (which I've so with no other NX hinbekommen so far). The AF is pumping almost not at all and summarizes the goal very quickly. I see the 45mm at the moment as a measure of things in Samsung lens program when it comes to AF for photos. I hope that all of the following will be at the same level.
The bokeh (the motion) of the lens is the 85mm of not dissimilar, thus very well suited for Freiastellung of Portaits because the 45mm in the center at maximum aperture is very sharp.
If the small restrictions would not, it would be perfect, so only almost. Since no 4.5 stars go, this time only 4. Who focusses on a fast AF should buy this lens without thinking, in the rating has the 45mm 5 star worthy.
The 45mm heard but next to the 12-24 one of my favorite lenses on the NX300 and the two are in the compilation of a well priced unbeatable combination