Shared hosting most likely wouldn't install it since it consumes a "lot" of RAM compared to what they usually allocate to a single user. The benefits for ES if it doesn't support your language are mainly:
1. Searching is faster, but not noticeably faster if you have less than 500K posts
2. You can search content with less than 3 characters (usually not useful)
3. You can enable "Warmers":
http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/indices-warmers.html
4. The search index is separate from your database. Not sure how much advantage it gives it terms of resources
I guess basically that's it.