The funny thing about AoW2 is that so many people have different experiences with it, and thus different perceptions of the game.
I've seen all of these comments in recent threads: "walls are useless", "archers are too weak", "sieges are just like any other battle"... "archers make for a powerful defense", "the only way to take 8-stacks of archers in city walls are with fliers", "halfling slingers shouldn't be able to take down 3-4 times their number"... Sure I'm oversimplifying it, but it's just kind of funny when opinions clash, because everyone's experiences differ so greatly. To clarify where I'm coming from, I've never had the opportunity to PBEM yet, and I've only played the campaign about 2/3 through, so my experiences are mostly with online play. In my opinion, theoretically, having 2 gates per side can actually be BENEFICIAL to some siege units (catapults and especially cannons). I've tried using them, and one thing I've found is they take too damn long to punch through a section of stone wall, and if they're unlucky, a section of wooden wall can tie them up too - but they're pretty good at smashing the GATES early so that your faster ground units can ride through and start taking down archers. A single cannon shot can actually blast down a gate often enough to be scary. In actual play, though, at least in my experiences, the siege units are too damn fragile to be consistent. Given their mediocre-ish defensive stats (except for the Steam Tank) and fire weakness, they get taken down too damn quickly to be really useful. I'd actually like to see their defense/hp boosted a bit, and maybe get rid of that fire weakness, so we could have another go at using them.
Again, that's just my take on it. And in case I wasn't clear, I LOVE the 2-gates-per-side implementation! I have a feeling it will be a big help for the AI (who always falls for the trick of having a unit led into the gates, and subseqently webbed/frozen/entangled in that spot to block up the gateway).