Right, from the start I need to disclose that Mafia II was one of the best games I had ever played. I own it on all platforms and have completed it many times on each.
Let's start at player models:
Vito - for anyone who doesn't know or remember, Vito Scaletta is the games protagonist. He has slightly visible frown and no eyelashes. None at all. His hair is in massive clumps of slightly textured black blobs. Now, in the remaster Vito has turned less pale and his face is a lot more detailed. If you look closely he still has no eyelashes for some reason but due to the lighting effects you can't really tell unless you look. His face is now much higher resolution allowing you to see single pores and patches of stubble. And his hair... His hair has probably changed the most. From lumps of black to single hairs, each hair is rendered in now instead of 10,000 like before. You can also see that his left cheek scar is much more prominent now. Vito's ears are also rounded now and not made up of straight lines anymore :)
Joe Barbaro - For anyone who doesn't know or remember Joe Barbaro is Vito's partner in crime, he got Vito into "the game" and is a snarky man. Joe was always rather fluffy if that makes sense. His hair was always clumpy and fluffy but not intentionally.
All of the other player models have just become more orange and have more accurate hair.
Now, the main game, surely the game looks spectacular now that it has been updated 9 years and 10 months later? No. Not really. Granted the game does look slightly refreshed and textures look less grainy and flat, however, there is one massive issue... Remember the boy on the corner of the street? He no longer has a voice. Aside from that terrible news and terrible attempt at humour the driving hasn't really changed but it does feel slightly different and the shooting still feels loose and like every gun is a spud gun which I thought they would have changed.
So, is it worth it? Should you get it? Seeing as steam is "upgrading" your original copies, yes you should reinstall it and at least try it. If you haven't bought it... Yes you should buy it. It is one of the greatest games made and really does a good job of making you feel like a bulletproof, slicked back and murderous man. If you think it will be expensive and break the bank, hmmm sort of. You can pick a copy for PC online for around £15-$20 and upgrade it through steam.