I'm assuming you like Spiral Knights: the game, and not Spiral Knights: the auction house dressup simulator. If you like the latter, EDF will do you nothing.

Some similarties:

• In SK, you crash on an alien planet and kill all the aliens because Spiral HQ told you to. In EDF, aliens invade your planet and you kill all the aliens because EDF HQ told you to.
• You fight robots, dumb creatures, and smarter aliens.
• Defeated enemies drop loot you'll need to collect lots of to get more weapons and gain more health.
• You got a vast arsenal of fantastical weaponry across swords, guns, and explosives.
• 2-4 weapon slots
• Healing is limited, and there's not many ways to regain health apart from picking up health boxes dropped by enemies.
• Guns are never hitscan. Most projectiles are slow enough that it's possible to individually dodge them.
• A key element to winning is managing aggro and stunlocking. Teamwork and tactics can be the difference between an hour-long slog and clearing a mission in twenty seconds.
• If you play online and meet strangers, a lot of them are really nice people.
• If you play earlier missions, your weapon level and armour level will reduce so you can play with new people without being too overpowered.
• Most weapons come in 3-5 different tiers, intended to be played at different difficulties and missions.
• One of the classes has a shield, and you fight/move more effectively by using your shield between attacks and dashes. One of the most popular shields is a lightweight, low-level shield that's faster than other shields.
• There's a gun called Thunder Sniper. It's got very few shots, but if you fire it at the correct angles you can hurt individual enemies extra by having the lightning bolts ricochet internally.
• There's a melee weapon that shoots explosions along the ground. It's very easy to use and defensively a very safe choice for old and new players alike.
• There's an immensly powerful rocket hammer that lets you dash and then inflict terrifying single-target damage.
• There's a really powerful bomb that every bomber used because it was good against almost everything. Later games nerfed it, but it's still pretty okay.
• There's four classes. Apart from standard normal shootyman who's been in the class since the beginning of the series, later games introduced a swift class equipped with an energy-draining jetpack, a heavy, slower class with shields and a more health, and a tactical class that can support their team and must rely on sneaky, underhanded tactics to win.
• There's a gatling gun that takes a bit of time to charge up, and you can't move while using it, but it can wreck crowds and single targets alike once you have it set up.
• There's a high-power, penetrating sniper rifle that's everyone's favorite ever since it received a huge buff. Before the huge buff, people didn't care much for it and sticked to switch-shooting with a different rifle.
• There's a fairly powerful sniper that's best used when equipping in both slots and swapping between each shot to increase its firerate, and all Ranger swore it was the only way to use guns. Some people still do it because it makes their egos feel good, but it's not as popular ever since all the other guns got buffed.
• There's an easy to use rocket launcher that's very popular with newbies because it's great at keeping you safe and good at killing all the enemies, but veterans are often angry at people bringing them because "all it does is throw enemies around instead of killing them". The weapon is no good at close range.
• I think it's a pretty good game.

Things EDF does better than Spiral Knights

• Apart from two (very interesting and well-worth) DLC campaigns, EDF will never try to extract money from you after you've bought it. It's not possible to end up spending 60 dolllars in a single weapon.
• Poor internet connection is handled much better, and even when I get unplayable lag in SK I get a completely smooth experience in EDF.
• Even if the dev's servers are down, I can still play offline.
• Local split-screen co-op.
• Nobody gives two craps about the game's versus mode.
• If a weapon is unbalanced, it's possible to mod the game and fix it.
• If a weapon is removed, it's possible to mod the game and bring it back.
• It's entirely possible to play through all of the game's missions exactly once and never grind.