the first 4-5 days of pretty actively playing Warframe can be a struggle, after that (if you invest in unlocking weapon/warframe slots on the go by spending a little $) you'll be crafting so many weapons and warframes at once that by the time you leveled them all to 30, you'll have another arsenal waiting for you. I dont think its that grindy at all considering how many frames and weapons you have to play with. sure the enemies aren't exactly memorable other than meat chunks that drop loot, but i had great fun customizing my frames and skills to see how effectively i could hunt those meat chunks. (edit: ill have to add that this is how i viewed enemies in hellgate london too. meat chunks that drop loot :P but still satisfying to kill thanks to character skills and customization)
I cant remember how long i played warframe, either 1 or 2 months and reached rank16-18 during that time. one of the rank quests made me almost quit the game, but after i managed to do it there were no big struggles beyond that. I also stopped worrying about my rank completely because the majority of the cool weapons were already unlocked.
edit: (why do i keep editing my posts...)
I have to say, the reason i think the first 5 days are the struggle period is not because the grind or any gameplay function, its the struggle with how poorly this game explains things to the player. Lot of UI elements could and still can use improvements so that players dont have to resort to wiki's or chat. Countless times i wondered what certain icons ment, or what ayatan treasures are supposed to be, just to give an example. the game does not bother explaining these things and expect you to already know. not to mention that the ayatan treasure window is tucked away in the strangest of places.. your mod facility. For a veteran this may sound like nitpicking, but as a new player this was very overwhelming.
i still think its a wonderful game worth giving a try, the only reason i quit it was because of my personal unhealthy habit of playing games non stop all day till i burn out.
