What I found fun:
- New Pets
- Quests that players of multiple levels were in the same area doing --so you could interact for once with guildies lower down the level curve
- the incentive to take down world bosses (though they should not be tauntable by a player who is not in the group that tagged the boss--especially if said player then repeatedly drags the boss to an evade/reset point)
- the newscasts and general sense of "something is happening"
- The continued story and flavor from Taris, Kaon and Lost Island
What I did not:
- Having to spend money on vaccine at lower levels when money is tight
- Getting flagged involuntarily for PVP on a PVE server by someone of the opposing faction exploding with the virus while you were standing around using the vendor for the event
- Having the vaccine not last through death (and getting infected repeatedly in PVP warzones)
- Having only one vendor for both factions on a PVE server--might be ok if there were a vendor with exclusively expertise stat items that the factions share, but don't force PvP on those who don't want it
- the short time frame, daily quest progression that penalized players who can only play weekends
- lack of notice of the event start and end date--in game email is better for many players or launcher messages
One thing they could have done is make quests you could do for experience to get vaccinated if you were low level, or you could pay the 2k by the time that is a trivial amount of credits to earn.
Players want to have control in the game, so anytime you take that away, it is less fun. Give people options, challenges and incentive to work together (especially across levels) with these events. For example, you could have an event of some kind of swoop relay race where the bikes are supplied by the game, so even a level 30 could particpate.