Dog Days is a considerably streamlined affair in comparison to the first game. There are no more heists, not much in the way of stealth missions, hell, there's not even much variety in the whys of what you're doing. You're pretty much always shooting and moving forward. In a way, this is refreshing - that other stuff was not executed well in the last game.
Of course, the flaw there is increased repetition. The shooting mechanic in Dog Days is more functional than it was in Dead Men, but it still feels a little behind the times in comparison to third person shooters in 2010, and the cover system still frustrates as much as it helps. This is compounded by weapons that have been hobbled in effectiveness by IO's desire to make them feel more realistic. Guns early in the game are inaccurate pieces of junk, and you'll spend as much time looking for better guns as you will your plan of attack. This is more a problem for you than the enemies you'll face, as Dog Days is one of the few games I've ever played where fodder opponents take more punishment than the player can.
The real draw of Kane & Lynch 2 is the story and presentation. At this point, you probably know about Dog Days' particular presentation style, evoking user created video content on sites like Youtube. However, the influence of modern and classic crime thrillers is also omni-present. Similar to the tonal similarities the original Kane & Lynch game shared with the film Heat, Dog Days evokes films like Collateral and The Departed.
Where the original game's narrative collapsed under its own weight about halfway through, Dog Days actually holds itself together remarkably well. It's rare that a game can make you flinch. Jump scares, sure. They're easy, and movies have made us all numb to them after the initial shock. But for a game to really crawl under your skin, to sit there and disturb you, where you'll watch awkwardly as a character sobs like everything has been taken from them, because it has, that's... unexpected. I'm unaccustomed to a game taking story seriously enough that it can actually be criticized for expending its emotional payload too early, or for descending so far into nihilistic violence that I felt like I needed to come up for air sometimes.
For PC players, there are other issues to contend with. Dog Days is a rough port from the console versions. The visuals look low res and choppy even maxed out - it's a pretty strange experience seeing such blocky image quality at 2560 x 1600 and 1920 x 1080 - with very limited graphical options. Worse, I experience major performance issues on my SLI equipped Core i7 system at work and my Core2Duo, Radeon 5850 system at home. The ATI system also demonstrated strange visual issues, including cutscenes that didn't actually appear. Instead, I got strange colors on the screen.
And then there's multiplayer, and its cousin Arcade mode. Multiplayer is broken down into three modes: The returning Fragile Alliance, and a pair of variations on the theme, Undercover Cop and Cops & Robbers. Fragile Alliance partners you with other players on a heist on a strict timetable. You've got four minutes to get in and out alive with as much money as you can collect, but there's a wrinkle; any player can betray the other players, collecting more cash. Of course, the payoff might be bigger working together, and traitors face the wrath of other players and enemy AI alike. Undercover Cop randomly assigns a Serpico amidst the expat thieves, who's goal is to stop the other players once the heist is in motion. Cops and Robbers divides players into opposing teams, with Robbers attempting to pull off a score and escape and Cops attempting to stop them. Arcade mode takes the multiplayer modes and fills them with bots.
While multiplayer's concepts are strong and interesting, they rely even more heavily on the shooting and cover aspect of Kane & Lynch 2 than single-player. It's nice that they're there, and fun can be had, but the online aspect fails to lift above its humble underpinnings. There is online co-op this time around though.
PC players will also likely be disappointed at the lack of dedicated servers. While Dog Days does feature voice chat, it doesn't support text communications, which some players may also find problematic.