To qualify for the special Series 1 reward - you'll need to play all of the episodes in Series 1 before Series 2 starts. (normal mission rewards can still be obtained anytime you play the mission in the future - the special reward is an additional bonus if you played them during their Live season - aka before they go into reruns)
Weekly episodes is the number one new feature I'm looking forward too. And as a casual, I really don't care so much about rewards as much as I care about getting good stories.
But when you consider that this game has always suffered for lack of content quantity, why would you implement rewards that encourage people to run through content as soon as it's released?
Multiple times it's been stated that one goal of weekly episodes is to "build up" a quantity of content so that someone new to the game, or who hasn't played in awhile, could log in, and have lots of new missions to play. Assigning rewards that are time-limited punishes those who do that -- not to mention the new players who will never have a chance at these "special rewards".
My level of disappointment will depend on exactly what these rewards are and whether they are available in some other way. If the reward is a usable item that has equivalents elsewhere in the game, I don't mind so much. But if it is a unique trophy that's not available any other way. I will be very disapointed.
Please consider carefully what these rewards will be and how they will be available.
I really don't see the issues people keep having with rewards/trophies/items/whatever that are only available for a limited time/limited group of people. What better way for Cryptic to encourage constant play (which means constant subscription) from their players than to have time-based rewards? Just as there was no better way to encourage the purchase of a lifetime subscription than by adding additional perks along with it. Just as they got us to give them our money by letting us play their game.
Its really no different, its simply business. Cryptic hasn't done everything perfect, so far, from either a business standpoint or from a player satisfaction standpoint, but nobody does.
If I'm not mistaken, I think Cryptic said the weekly missions will be available anytime after they're added.
Also, as for constantly playing, I don't think that'd be to great a deal, we don't want to have to be rooted on this game, particularly since real life does take priority, and not only that, but there are other games to be played as well.