Is it true that obstruents and nasals are unreleased word finally in English?
Obstruents and nasals unreleased word finally.
In many varieties of English, final consonants are pronounced quite differently from initial or medial ones. I'll use my variety (Canadian English) as an example. Stops are all unreleased word finally, except for special emphasis. /t/ is generally realized as [?] word finally, though it often becomes  if the following word begins with a vowel and is part of the same phrase. Voiced stops are often partially devoiced, though they always contrast with voiceless ones. Fricatives and affricates seem to be essentially the same in intial and final position, though partial devoicing may apply, as with stops. Nasals are a little different; /n/ is often elided word finally and pre-consonantally, but its nasality is transferred to the preceeding vowel. /m/ does this too, but much less often; I don't think /N/ does (though of course unstressed -ing often occurs as [I~] because of the form /In/.