Well, parts of match/wheel/flintlocks don't move when firing/reloading and animation for reloading pistols is the same as for muskets.
Also, there is no delay between pulling the trigger, ignition of powder in a pan and firing which is like firing modern firearm and not musket.
Other than that it is not too bad. Bows however own any firearms in multilayer.
Oh, and there are no Ottomans, it's Crimean Khanate. There are also Ukrainian Cossacks.
Their big selling point was a unique quest line for the first "addon", actually 3 unrelated quest-lines. And I personally think it sucked big time, on top of that the quest-line is both buggy(still!) and capable to end because you did something it did not expect you to do (developers don't agree that is a bug).
Quest-lines are for Cossacks, Poles and Russians.