Depends on who is looking at it. Those who are new to video editing or photo editing may not be used to 'pixel peeking' which; is sort of like giving the image a close examination. Videos I shot years ago in 720 looked great to me then, now I can't believe how low resolution they are. 4K is essentially 4 times the resolution - twice as tall and twice as wide as 1920 x 1080 hence the pixels of 4K are 3840 x 2160.
While not everyone can view true 4K there are an overwhelming number of reasons to shoot at that resolution. As I mentioned, down the road 4K will be the norm and 1080 will look very dated at some point - some would ague that we are already there but I don't think that is the case just yet. I started shooting everything in 4K a year ago when I got all of my other camera gear up to speed.
I believe a 4K clip down-sampled to 1080 in a proper editor will retain a better picture and has more potential, than a clip that is shot originally in 1080. Video sites like Youtube, when given a full 4K video produce smaller versions so a larger audience can participate in viewing, and I believe that even Youtubes' 1080 version of my 4K videos look better than videos I shot just two years ago in 1080 like my First Typhoon videos. Now some of the reason for that is of course I am shooting with much better cameras now.
Long story short, yes; 4K will ultimately look much better especially if you can actually see in full size. As Flush mentioned, once you get enough computer to work with 4K, you'll be glad and never look back.
P.S. not to take this thread too far off track but for those new to editing, some editors now, such as Power Director, allow the use of 'proxies' - basically the editor makes a low resolution version of your clip so it is easy to work with while your putting things on the time line and scrubbing through them. When making the final edit - PD then uses the actual clip and makes any changes you put into the proxy - into the full clip as it renders out. This used to be one of the pluses of using pro editing suites like Adobe years ago but now it is a boon to allow even moderate computers to work with 4K. Though the render times can take a very long time.