I am trying to install RSense for vim in fedora. I read this manual. I downloaded the tar ball of rsense and extracted it. Then I copied it to the root/opt directory as given on that page. Then I made a directory vim/plugin in the opt directory and copied the rsense.vim in the plugin directory. But when I write :RSenseVersion in the vim editor,I get a message that the command is not recognized.What have I missed ?
Till now I have not installed vim-ruby plugin as staged on the documentation page. What is this plugin meant for ? Can’t RSense alone solve my purpose of writing a neat ruby code with auto-completion,code hinting ?

No, you didn’t read the manual.
Once all the dependancies are dealt with you must put the plugin in
~/.vim/plugin.As for the differences between vim-ruby and RSense, I don’t do Ruby so I don’t know for sure. Looking quickly at their doc, it looks like they are very different in scope and have slightly overlapping features. I’d install both: vim-ruby for all the low-level Vim tuning and RSense for its supposed code intelligence.
But I have a feeling none of them will help you write “neat” ruby code. Only your programing/ruby skills will.