Nowadays Sardinian is spoken together with Italian especially in the central and southern regions of the island, and is considered endangered because the number of its speakers is declining all the time.
The pronunciation of Sardinian can seem a little bit strange for a Romance language: it uses dd instead of Latin ll in the middle of the word, bb instead of Latin qu, and lots of other changes of initial and middle consonants, some of which are obviously non-Indo-European. But in fact, the phonetics in whole remained quite archaic and keeps many Latin original sounds.
The grammar is also archaic preserving many of Latin or Popular Latin inflections and forms, e.g. the 3rd person singular -t of verbs. Genders are kept, as well as many Latin tenses and verbal forms: infinitive has -re ending. Even the noun and adjective ending -u means a relict of Latin -us lost in all other Romance tongues. The definite article was formed from Latin ipse, while other Romance languages used ille to form it.
The Sardinian vocabulary contains most words directly from Classical Latin, not from Popular Latin. "To know" means iskire from Latin scire, while French and Spanish use another word from Latin sabere. Many Sardinian words are originated from pre-Indo-European languages, like cùccuru "peak (of a mountain)", or tilipirke "grasshopper". Some words were also borrowed from Spanish and Catalan, but their number is still very small.