Personally, I'm in favour of offense
I do think that Brawl will have more defensive potential, but it'll still have a very important offense. Certainly, Brawl will become a less crazy game, not just because the game is slower but because players will have to play slower and more methodically. Poking will become much more prevalent and, like...like...dammit, I forget your name. >< Well, the guy that talked about range. It'll be even more important than in Melee, because the last thing you'll want to do is get closer to your opponent.
Reduced hitstun certainly makes shieldgrabbing more viable, but at the same time it makes shieldgrabbing somewhat of a less effective counter. Once you grab someone, if you don't throw them in time they'll break free. So we come to the throw. People can act sooner after being thrown, making it tougher to setup effective counterattacks out of down or up throws. Yes, there are also forward and back throws, but we've already seen something that can help with anti-throw options, working alongside DI.
I'm just going to fall it "Fair DI", although that's a crappy name, because I've seen it as a Mario doing his fair and literally halting his movement away from the stage, and even increase his speed while approaching the stage (this is actually one of a number of things I've seen that make me think we'll have more control over our characters' momentum than we've ever had before).
Also, the new L-cancel might very well help to balance the increased ease (and thus, prevalence) of shieldgrabbing. Now SHFFLs have the potential to be faster than they've ever been, and that might just be the key to maintaining composure and control over a defensive opponent.
For example: a Samus FFs her dair on a shielding Mario, thinking that she might be able to break the shield given its current size. She misjudges and Mario's shield is just barely intact, while Samus hits the ground still in her dair animation but just after the attack connected. Mario may have less hitstun than in Melee, but he's still got some, whereas Samus' dair cancels all of her lag, allowing her to d-tilt Mario through his shield and send him flying before he can grab.
Anyway, the improved ease of shieldgrabbing will nevertheless make for a more...not methodically paced, but methodically played game. We'll certainly have to think more about our offense and all-out offenses will become less common. This means that various attacks will gain prevalence for different reasons.
Jabs will become more important because they can be used to eat through shields with rapid but correctly spaced, or even down-cancelled, jabs. Or, they can be used to take advantage of hitstun and get in a quick close-range grab against the shielding opponent.
Tilts and projectiles will become more important because of their range and speed; they can outreach shielding opponents. Incidentally, their use will force players to move closer.
Also, Link and Samus will gain an advantage because their grabs are long-range.
Smashes will become more important because they push your shielding opponent away from you, and do the most shield damage on average.
Multi-hit attacks will become more important because of the hitstun and shield damage.
And all of this only applies to the ground. In the air, you can't shield, so the game will change drastically between air and ground fighting. Ground combat will become much more spaced out and defensive, while air combat, with its lack of shielding, less lag and new airdodge, will make for some terrific dogfights (and since there's so much less defense in the air, air combat will certainly become...*drum roll*...more important in the game).
Characters that have reach in any form, be it a long dashgrab range (which fast characters have), a long attack range (swordsmen), very fast attacks (Metaknight--he won't have any problems versus shieldgrabbing, because he can just stay at tip range and rip shields to pieces) or projectiles (Samus, Link, Pit, Snake) will have very obvious offensive advantages. Techniques like the Dash Brake will gain prevalence (running to your opponent, only to stop and watch them grab at nothing, and F-smashing them right in the face, for example).
And, of course, none of this is even taking the opponent's actions into account. Nobody shields, grabs and dodges forever. Especially not if they're being attacked either from a distance or with a flurry of attacks that shielding simply won't deal with. What does that result in? Offense, but tactical offense.
Edit: Using the same principles as described above, except while taking into account their effects on opponents who, at the time, aren't shielding. And since both players are thinking about this, tactical offense will not only include what you do with your offense against your opponent's defense but also what you do against your opponent's offense.
And that, IMO will be the big change from Melee to Brawl. Crazy, high-speed offense to slower, more involved and active (since we can act faster), tactical offense, in the face of improved defense. Same thing with edgeguarding, since it's easier to recover.
Not just that, stopping your opponent from being ridiculous with shielding is as simple as doing a tilt (or any other attack). As long as your opponent is shielding, he/she is stationary, which means that he/she will have to stop shielding to do whatever sooner or later. Early on in the metagame, assuming we don't discover some new techs that change the game completely, the prevalence of poking will create a deterrence for turtling, which will in turn sustain the offensive nature of the game.
