Single driver speakers. Are they worth considering ?

What they more or less avoid, as compared to multi-way systems, is comb-filter problems of two or more drivers interfering with each other.  

The Comb filtering is what causes dips off axis.  Hence poor dispersion. 

I built these Aveburys by Woden Design, using Mark Audio 12p drivers.
https://www.wodendesign.com/avebury.html
In the UK you can get great advice directly from the designer and from KJF Audio who can supply all the hardware. About £250 for the drivers and other bits and pieces, £80 for the plans, and £150 for quality ply. And the cost of your own time over a couple of weekends. For that money and time it is easy to find out just how great a back loaded full range horn can sound.  If you have the space of course - one of the routes out of the compromises is a very big cabinet. These are 6’ high. 

NO i will pass like great bass detail and highs.

I'd rather pass a gallstone HA. Actually I have single-driver speakers, of course it's all in the application as anything else. Plus we choose our compromises.

Once you listen to a single driver speaker, you will never go back to a multi-driver speaker that is nothing more than a symphony of disjointed monstrosity :-)