If you liked the first one you should check it out. It seems all these useless reviews were written by people who didn't even care about the original. Catalyst pretty much improves upon every aspect.
The open world is absolutely fine even if you don't want to indulge in it. If you just strictly follow all the main missions it's basically the same experience except that you have to run to the start point of every mission. But isn't running the point of the game anyway?
Speaking of running, it's as fluid as it ever was and you will get the same rush you got from the original. The openess of the environment makes it even more enjoyable since you can find your own routes. The original was way too linear in that aspect.
I don't understand the issue with the combat. They expanded quite a bit on it and made it into an art itself. It's much more involved and tactical and needs actual skill this time around. Maybe that's why people didn't like it?
For now I will stick to the main missions to completion so I can be fully leveled up and indulge in the many many time trials which are as challenging as ever.
I'm not sold on it. I liked the linear laid out parkour challenge of the first one, not interested in finding my own path in a bland open city. Levelling up is a horrible addition as well, and I would have liked to see much less combat, more avoidance, not an overhaul and engagement. I'm simply not interested in combat. Even Uncharted 4 has taken a turn for the worse for me in the final chapters, forced to fight wave after wave, no more stealth jumping around puzzling allowed.
At least the time trials are still there? Second hand or steam sale I guess.