ARMA 3 is not polished enough and it feels unfinished, but still it has a lot of premise.
As for the quality of ARMA 3, an extraordinarily rocky development process hasn't held things back too much, all things considered. Infantry mechanics work well, with the exception of terrain collision, which leads to the player getting stuck or AI glitching into the ground on a semi-regular basis. Vehicles also generally work as intended, but I find that their damage models feel rather abrupt and inconsistent, and this results in many a sudden and unexpected fiery death. The maps are generally very nice, but Altis could use more in the way of unique landmarks, and disappointingly most of its few unique buildings cannot be entered.
All in all, ARMA 3 generally accomplishes what it has set out to do, but to some extent its overall fidelity makes those few deficiencies all the more glaring. If you have missed out on joining the Alpha or Beta (and thus buying it at a discount), I would recommend that you wait to purchase ARMA 3 until they add more content. It's not exactly what one would call a "full game" in its current state, even though the price has increased substantially with this "official release". However, for those who have bought this game months ago like myself, it's a great value that will continue to pay off for a long time.