Probably the best game I've played on the PS4 this year. It's open world, and yes seems inspired heavily by other franchises like Assassin's Creed and the Batman series of games, particularly for combat - which it easily equals in style. However where Shadow shines is in the new 'Nemesis' system, which really adds a new depth to the game, and a real cost to dying. You're fighting the constantly changing Sauron's army, with Orcs that rank up and gain new attributes and skills if they defeat you, or simply if enough in-game time passes. The majority of the Orcs seem to be randomly generated too, with some fantastic character modelling and an amazing amount of varied dialogue they'll spit out at you. For the LOTR nerds out there there's also a bunch of completionist stuff to do, collecting artefacts and hidden sigils in the map that give you interesting bits of back story in the form of well acted voice dialogue. Various characters you'll recognise appear too, again with some superb voice acting.
This game has some real legs to it too, I've played over 9 hours now and haven't even completed 50% of the story missions because it's just fun messing around in the open world. The Nemesis system also creates randomly designed missions to populate the map depending on the Orc captains, bodyguards and warchiefs you've fighting against. You can gate crash a grog drinking party, or dive into one captain trying to ambush another etc. and just generally make yourself a nuisance to Sauron's army.
The game has some serious challenge as well. Killing warchiefs or even ranked up captains is not a walk in the park, you will die unless you spend some time researching your opponents and scouting the territory (which is where stealth play often comes into focus). The PS4 version really stands up well too, I've been in battles featuring more 30 Orcs on screen at once without any noticeable slow down or lag.
Absolutely a must buy if you've enjoyed the Batman games and are a fan of LOTR, or the Peter Jackson movies. Beware that it is very heavily combat oriented though, you're a Ranger in Mordor and will butcher thousands of different Orcs and die in very messy ways yourself along the way. So if that's not your cup of tea perhaps try something else.