On a somewhat tangential note, I don't really like the "1 to 5 stars rating" system, which seems to be so prevalent.
If you see this rating, how would you interpret it?
Most people would interpret it as average, pretty much exactly half-way between the minimum and maximum.
Would you, however, believe that that rating is the result of two 5-star ratings and four 1-star ratings? (Which, in other words, means that twice as many people gave it a minimum rating than a maximum rating.)
How so? That seems impossible and completely unintuitive, right?
The average of all those ratings is (1+1+1+1+5+5)/6 = 2.33, which rounding to the nearest half-star gives indeed 2.5 stars. Yet, it still feels very unintuitive, and hard to understand how such an imbalance in ratings can put the bar exactly in the middle.
And that's what I consider somewhat of a problem. The star bar rating gives a false impression of how it has been rated. It gives the impression that the ratings are about evenly split, when they clearly are not.
The problem is that 1 is the minimum rating. Which in turn means that the leftmost star is
always "lit". Even if every single rating was the minimum, it will still be lit. This gives a misleading visual representation.
If the leftmost star is removed, it suddenly gives a much more intuitive visual cue that corresponds more to the idea of four minimum ratings and two maximums:
Another (perhaps better) solution is to allow for 0-star ratings (which means that even with 5 stars, the leftmost one can be off, or only half filled.)