SWAT 4 provides more of the same intense tactical shooter action SWAT 3 had. There's not much of a difference between the two, but if SWAT 3 left you wanting more, buying this game is a no-brainer. Although a little inferior to SWAT 3 in terms of mission design, it still stand as one of the best games in the genre, and you shouldn't hesitate to buy it at full the asking price.
DON'T BUY THIS GAME. The game ends after just 1 mission (tutorial). The credits just starts rolling... It's apparently a known bug that came out with the patch 1.07, and is only fixed if you buy the Japanese DLC. If you're like me, and just have the Vanilla version of the game (with the 4 dlc missions), then you won't be able to play the game after the tutorial mission. Be sure to check out the GOG forums on this game, and search the internet before spending money on this title, unless you also plan to buy the Japanese DLC (which again I can't vouch for it fixing it but that's what the word is).
I wrote a review of this game on BetweenLifeAndGames, and I was going to copy/paste my review here, but it won't fit as it's too long. You can find it here: betweenlifeandgames(dot)com/indie-corner/indie-game-mini-review-swapper/ I hope you find it useful in deciding whether or not to buy The Swapper.
www(dot)neogaf(dot)com/forum/showthread.php?t=700177