1) Nonsensical story (and poor follow up introduction levels.) Just sort of tosses you in and expects you to play, but I really have no idea whats going on.
2) Forced matchmaking after the very first level(?) The game dropped me in with 1-3 other people for these missions, who are clearly on alt accounts or something just speedrunning to the objectives, blowing past everything while I'm still trying to figure out exactly what's going on. This does not a good experience make.
3) Secondary systems (i.e. everything not combat) are not explained well, if at all. You just sort of unlock them over the course of the few missions, and seem to be expected to know how to use them (despite them still seeming fairly limited.)
Yes, this is my experience too.
I think this is the second or maybe third time I give Warframe a chance, but I still find it a rather confusing experience. The UI feels cluttered and messy. There are obviously various systems in place, but I'm not sure what many of them do.
The most frustrating bit is finding my way around, though. The levels/maps are like mazes and other players just blitz through them. After a while I get a message that the others are waiting for me at the exit and I'm like "I'm sorry, but I don't know where to go!".
I made it to the Plains, but I don't know. This still feels rough and unpolished to me.