I just got ME2 for the PS3 and i was wondering if the weapons and armor DLC worth it or not.

This is my third playthrough, going through insanity now.

The only worthwhile armor DLC is the Aegis Pack, which gives you the modular Kestrel armor parts. Each part has awesome bonusses, which are pretty good if you play an Infiltrator character (which on Insanity you should).

Other than that, the other armors and weapons aren't that useful, especially since the only weapon you'll ever need in ME2 is the Widowmaker xD.
If you're more into heavy pistols or assault rifles though, you could give the Firepower Pack a try, since the M-5 Phalanx Heavy Pistol and the M-96 Mattock Heavy Rifle are the best on their category, plus it comes with the Geth Plasma Shotgun, but I never tried that one since I'm not a shotgun guy myself.

On my Insanity playthrough, had it not been for that portable nuclear weapon (can't think of the name of it), I don't think I would have made it. I think the flamethrower was DLC, too. It was a HUUUUUUUGE help when I was facing off with those Husks.

I hate these armour/weapon DLCs, they're either completely OP or utterly useless, make me feel like that I'm paying for cheats >_>.

besides, lestatdark already said it, nothing beats the Jim Raynor Sniper Rifle.

You mean the M-920 Cain right? That thing is a beast, though it chews up Heavy Weapon ammo like it was candy >_<.

The M-451 Firestorm, the flamewthrower, was part of the Zaeed DLC, so it should be already part of the PS3 version of ME2.

I never fired a single shot from the portable nuke on insanity, I just don't trust the mega slow charging time.

personally my favourite heavy weapon is that lightning gun, it stuns and disables enemies for a short time.

The charge time isn't too bad.  It took me a while to figure out how to use the thing, to be honest.  It required probably 100% or more ammo to fire a shot, otherwise it just made a steam engine sound.