I have not played any of the previous three SWAT games so I can't tell you how much it may have improved. What I can tell you though is how good this version is. The training mode does an excellent job of making the complicated looking controls very easy to use. You'll find yourself performing clever strategic moves in no time at all. And you'll need to. Even the first few levels need a certain degree of brain work and quick reflexes to prevent your team members getting killed.
As well as different types of grenades and guns at your disposal, lock picks, spy mirrors, handcuffs and vocal commands all need to be used at the correct places. If you just go charging in shooting everything you will lose. The bad guys will shoot the hostages, destroy what you are looking for, or shoot you before you get very far into the level.
The levels themselves are well designed are very varied in where they are set. One particularly eerie level sees you creeping around the basement of a psychopath's house. He has kidnapped his latest victim in a scenario very similar to Buffalo Bill in Silence of the Lambs. There are pieces of human skin hanging from the ceilings and lots of hidden corners for you to carefully search out. It took me a few attempts to do this level and what I liked about it was that each time I tried again, the bad guy was in a different room. So you can't just charge in thinking you know where he is.
There are a couple of small problems in SWAT 4 though. You have to click on things like discovered hostages and then select from a menu what you want to do. Unfortunately I found that I had to edge about slightly until the cursor would change so that the menu could be called up. This was very fiddly and on a couple of occasions wouldn't work at all. My other problem is that you may enter a room, shout at the occupants to get down on the floor, or shoot them, and people in the next room often seem to be completely oblivious to what's happening. These are only small problems though.
This is a great game if you want to use a bit of strategy and stealth. It's not as good as Brothers In Arms for strategy action or Splinter Cell: Chaos theory for tense sneaking about, but it's still well worth a look.