I think the out-of-5 rating is a waste of time because there's no room to move. If you're doing it out of 10 you can at least have shades of opinion but with 5 you'll frequently have to compromise.
We have the 1/2 rating option, so, I just condense my out of 10 ratings into an out of 5 rating. I've been trying to stay consistent between here and IMDb, so, my 7/10 there is a 3.5/5 here.
Just in general...
To me, these ratings are subjective. That means they vary based on the mood I'm in or the company I'm with, when I see a given film. It's just a review of a first impression a movie made on me. I am happy to dish out 1/5 or 5/5.
I'd hate to see every movie as a 2.5/5 to 3.5/5. I'd be miserable, knowing I almost never enjoy or experience anything to its best or worst. I would start to wonder, why I can't hone in on my tastes more adequately and why I'm unable to hit better movies for me, ones that connect with my taste, with a much higher frequency. Unless, I just like to complain and prefer not to like or dislike anything fully. Maybe it's the fault of most films, that they are only average.
Maybe I've seen too many films and nothing moves me anymore. A 3/5 just always feels like I'm sitting on the fence.
I try to use my better judgement and try not to watch something I know I'll hate, even before I start. That pretty much limits my ratings to the top half of the 5/5 scale.
On the forum, I actually prefer reading reviews with ratings that either tank or soar. They tend to bring out more emotion in the reader and often promote more discussion. I tend to ignore the middle of the road, long-winded neutral drivel and analysis. I also prefer short reviews.