Its my first MMO, so far I'm loving it.
I'm pretty lost most of the time though, I just seem to go from mission to mission. Not sure how mods work yet and what the whole point is other than playing the story and co-op missions. The Arkfalls are boring, you just run around for 15 minutes killing enemies and shooting at a crystal.
The first area is very easy to get lost in, it's huge and it's probably got more real estate than the map gives it credit for. The Arkfalls change up a bit, some are destroy the crystal and others are destroy waves, the major Arkfall changes it up with a big Boss at the final Arkfall that spawns after the last minor Arkfall in the area gets taken down. I like going for the top score, if I know I'm not going to get it, I go for a top 20 ranking. With my style of aggressive DPS I hit the top 20 fairly easily. The major Arkfalls reward you with one or two loots at the end, somewhat more worth it than the minor Arkfalls.
What I spend a fair amount of time doing is going from shop to shop, looking for goodies. Mods don't really benefit you early on but they are nice when you get a really good gun you like. There are only a few funky weapons that really need a mod or two to work well, like flare guns or grenade launchers. Once you unlock all the salvage matrix features you can add more mod slots, so everything can be modded to your liking.
The FRC SAW(LMG) works way better with a full set of mods, recoil down, dmg up, mag cap up and a sight for accuracy. Flare guns default to a 1 round mag, the lowest pistol mag mod gives you +4 capacity, now you have a flare gun you can use for crowd control. Manual detonator grenade launchers can get an extra grenade or two by modding the magazine, a necessary mod to make it awesome. Once you build your gun around your perks you'll start to realize how modding will work for you.