Can I just take a moment to say that? I love the way it is designed and I'd like to give a little praise to Spiral Knights' design team.

What do I like about it?

The Guardian: Usually, when you see a tank class in games, it's either this overpowered juggernaut that can wade solo into battle and never die while still kicking everything else' butts, or it will be something ineffectual that relies completely on support from other classes to tank at all, but in Lockdown the Guardian starts off as a decent, few strengths-no-weaknesses weapon-wise (really, can you consider a gun attack penalty to be a weakness? You can't even notice the difference) and has a class-defining ability that lets him tank anything (so it is useful) but only to a very limited quantity (so it's not OP). In addition I love how much of a team-support guy he is. A guardian by itself can try to play the defend-and-counter-attack game if he's fighting one on one, and is also probably the only class that isn't immediately doomed if he becomes stunned or frozen, but against a more skilled opponent or multiple enemies he can't do much except buy time and prevent a point from being captured until help arrives. But with allies, he suddenly can go from shielding himself to being the catalyst that allows another person to attack freely without fear of being damaged, for a brief time (compareable to the Medic of Team Fortress 2 and his ubercharge) or he can help himself and his team regenerate away small injuries without them having to leave a point unguarded.

The Recon: In other games, their approach to the "spy" class is always the same. He'll be a class with an obnoxiously cheap, instant kill attack, who has absolutely no need for the help of his teammates and never helps them in any way other than simply killing the enemy before they get there. The Lockdown Recon class, on the other hand, takes the unique approach of an armor-cancelling debuff. Instead of killing people himself, he makes them easier to kill, which means he helps his allies out as much as he helps himself, and is in fact far more deadly when he has friends there to pounce on his targets with him the moment they become weakened. I love the way, in particular, that his armor-negating debuff allows him and his allies to use ANY weapon they want regardless of their opponent's defenses; I could run into someone with all drake-scale or jelly armor when I have a Rigadoon equipped, and be all "oh no, it will take me forever to kill this guy!" and then a Recon can sap his armor and he'll go down in a couple attacks. On the other hand, the debuff doesn't seem to make any difference to the Guardian's shield, allowing them to successfully counter a particularly deadly assassin. I also love that while the invisibility is complete, can be maintained for a long time, and can be activated in the middle of combat, that the pre-debuff warning lets enemies know if there's a recon guy lurking nearby, and that he loses all of his stealth power if he's struck while it is active.

The Striker: Deadly, but made of paper. That part isn't exactly revolutionary for a fast-moving class. What I like about the design of the Striker class is that his get-out-of-trouble-free dash ability can only be used for such a comparitively short amount at a time. Sure, you can dash straight from one point halfway across the map to the other in no time at all, but by the time you get there you're completely vulnerable for a few seconds, with no dash energy, no other defenses, and a low max health. If you find a pack of enemies when you get there, you are toast. You can also dash away from danger, but your power reserves are mostly just enough to get you away; you can do hit-and-run tactics but only to a small degree, especially considering that huge neon energy trail you leave behind you... you aren't sneaking up on anyone. That means that despite your deadliness, a guardian can see you coming and get his shield up, while a recon guy can just stay hidden in the corner and let you run right by (and then blast you as soon as you run out of juice, go invisible again and sneak away before your dash energy has recharged again)

Altogether we've got these three classes that have fairly well-rounded basic combat abilities and three very distinct, very potent, but limited special abilities that all balance each other out and reward good teamwork. Great job!