Using an ip address instead of a domain name has only one advantage:
>> loading speed.
In order for your browser to load the content of a web page, the site's url has to be resolved. This might take from hundreds of milliseconds to few seconds. Using an IP will simply skip the reverse lookup operation and load the site content immediately.
On the other hand, this trick is search engine and user unfriendly. Your ranking in search engines is affected as these recommend using words of a significance in a url string.
