10 Springfield 1903/05
The biggest upgrade is definitely the maps.
The third was decent enough but pretty basic. This is just sprawling and open to multiple tactics for success which just adds replay value. Loving the sound stage and graphically it's above par. Given their an indie studio with a low budget I don't care if it isn't amazing in either department as it's the gameplay that counts and this is easily the best entry so far.
More of the same but nice tweaks here and there. Anyone tried multiplayer yet? The third game was broken for months before they fixed it but I put that down to inexperience on the new platforms.
After last night I'm on mission 5 and it's starting to feel more like the older games because my head has clicked somewhat with how the maps are designed. They are indeed open and you can tackle objectives in any order should you choose too but so far they're also... circuits. The levels so far have each dropped you in an opening area and then the objectives are effectively in a circle. If you work you're way one way round the game suddenly snaps into being much like the earlier games.