Please do not punch the panda... too much.
I remember the moment I read about it in the news: 2010, San Diego Comic-Con, Capcom, Announcement: Street Fighter X Tekken. My initial reaction: Whaaaa???!!! How did Capcom and Namco even sign off on this?! I remember the Japan-only strategy RPG Namco X Capcom, but this is crazy talk! If this is a desperation move, then it's the weirdest, most awesomest cross-over fighting-extravaganza desperation move I've ever heard. Give me the panda now. I want to Hurricane Kick it.
(Also, that's Street Fighter “Cross” Tekken, not Street Figher “X” Tekken. It's kinda like matrix multiplication, but let's not stretch that analogy or I'll probably lose you.)
Since the crowds at E3 swarmed around the Street Fighter X Tekken stations without much wiggle room, I was pleasantly surprised to have at least a half an hour (roughly eight or so matches) with the preview build of the game, complete with two tournament sticks, at a snazzy Capcom event in San Francisco. As an avid fan of both Street Fighter and Tekken, I couldn't ask for a better way to see how Capcom has molded the Tekken characters into its Street Fighter cast. While Capcom may have an easier, though still difficult, time editing out and refining the moves of Tekken characters for Street Fighter X Tekken—as opposed to Tekken X Street Fighter where Namco has to create more than a handful of new moves for Street Fighter characters—the title is well on its way on being a hit with both casual and hardcore fighting fans.
In essence, Street Fighter X Tekken places the Street Fighter IV engine into the Tekken Tag Tournament frame and cranks it up fairly close to Marvel vs. Capcom 3 speed. The point is still to pulverize the opposing team on a sprite-based 2D plane with 3D graphics, but as it is in Tekken Tag Tournament, matches are won by knocking out only one character and it's best out of two. This means that well-contended matches are normally twice as long as they are in Street Fighter IV (timeouts occurred often in the matches I played) and that combo strings and juggles are essential.
Luckily, practically anyone can pull of the most basic string, which like in Marvel vs. Capcom 3, consists of a continuous light, medium, heavy, and launch (that's heavy punch and heavy kick together) attack without the need for expert timing between hit windows. As usual, launchers are a huge “risk vs. reward” maneuver: If it hits, it can start a chain that inflicts massive damage and can even include another launcher attack, but if it fails to connect, your character is wide open for a counter chain. So noting the difference between actual health and recoverable health throughout the match is key, because facing an opponent that knows a crazy juggle effectively means that your health bar is chopped off by at least a fourth.
Tekken also makes an imprint in numerous ways, particularly because all of the Tekken characters shown did not have any projectiles, as they shouldn't (though Kazuya can dissipate projectiles with a sharp punch). There is word that Tekken characters can be controlled using the optional four-button input familiar for fans of the series, but we weren't able to check it out, so it remains to be seen whether it will be too jarring to switch between two control schemes.
Apart from that, it's pretty much as expected for a Street Fighter title, with grittier graphics and noticeably faster jump-ins. The normally extensive movelists for Tekken characters have been pared down to several normal combos and special attacks to fit with the roster, which currently has 14 characters (Ryu, Ken, Guile, Chun-Li, Sagat, Abel, Cammy, Marduk, King, Julia, Kazuya, Nina, Bob, and Julia).
Special attacks can be upgraded to an EX move or a charged move, super attacks use two units of the three-segmented special gauge, and the characters between developers have specific rivalries. Beyond the featured Ryu vs. Kazuya matchup (though I think Ryu vs. Jin makes more since given their Evil forms), I can see Chun-Li vs. Ling Xiaoyu, Crimson Viper vs. Nina, Ken vs. Paul, Fei Long vs. Law, Rufus vs. Bob, and Servbot vs. Gon (oh, that would be the most annoying team ever). Doesn't a Street Figher X Tekken make more sense, now?
In various interviews, Capcom has already mentioned that they would like to change the lifebars, which has an orange bar with an orange glowing overlay (not good), and that they're thinking about including Street Fighter characters outside of IV. Whatever the case may be, look out for my Abel/King team to kick a lot of cross-over ass in Street Fighter X Tekken, coming early 2012.