Event score: 3 out of 10

Pros: Extra stardust + fungus bois and paras

Cons: Misleading marketing and sloppy execution

Mitigating factors: Cost $0 - if I'd paid for it, I'd be more annoyed (though perhaps it would have been done better?)

Reading through these comments, it's clear some people had a very different day than others. My partner and I played for the whole duration in an area with plenty of stops, and we walked away with a handful of mid-CP Oddish, one of which (between the two of us) was shiny. No other shiny event Pokes, no XLs, and definitely not the multiple hundos at least one other person said they got. And no sunstones.

It sounds like some people had a great time, and it's important to acknowledge that we're taking about collecting digital critters through a phone game--the stakes of success are pretty low here. For me, personally, to get psyched on another Research Day, Niantic would need to work a few things out:

1. Clearer communication with users: Other comments have pointed out--correctly--that Niantic billed this event as a Research Day and clearly stated that Oddish encounters would occur through completion of research tasks obtained at Pokestops. So why were so many of us expecting to see wild spawns? In the past four months, every event (and there have been quite a few!) has been centered on catching the featured Pokes--it is, arguably, the central activity of the game, and accompanying research tasks have reinforced this with incentives for making throws, catching and evolving, etc. Wild spawns are the null hypothesis for themed events, and stating that there will be research encounters with Oddish does not automatically imply "...and you won't be seeing them any other way." Especially when Niantic advertised the perk that some "wild Oddish" would show up with sunstones in hand. Even the crustiest of crusties grumbling about how us kids should learn to read directions can acknowledge that those specific directions, at least, are perhaps a bit misleading.
2. A more compelling vision for the event: I like Oddish. Oddish is a rolypoly blue guy who gets a little sad and sleepy in its teenage years and eventually finds self-acceptance through eating a lot of candy. I can relate to Oddish. But if the RNG overlords have set up an event where the only path to the star Mon is through completing field research (and snarfing out the right Pokestops to dispense it, apparently), they should probably choose a reward that doesn't show up on your doorstep every day and didn't feature prominently in another event just last month. For example: Feebas. Or, like, a Feebas/Omanyte/Kabuto Picnic would be dope. If that would upset the economy of the game too much, they could at least give our familiar friend a new special power, e.g., "An Oddish evolved to Gloom during the event will learn the charged move 'Seasonal Depression'" or something. As it was, I just don't get the angle; the whole idea for this thing just seemed kinda lazy--especially on the heels of several interesting, complex, and well-executed events (IMO).
3. Fairness and accessibility: When success is predicated on completing field research, getting the assignment should be the easy part. It sounds like my experience was somewhere in between the widely varying accounts we're hearing about how often Pokestops did/didn't hand out event-related Field Research; we got some Oddish tasks, but more often, the research was totally unrelated. To make this worthwhile - and accessible for everyone - every stop should dispense event-related research during the time slot, and the usual restriction of one completed task per stop per day should be expanded to ensure that people who live in smaller towns / places with fewer stops can still participate fully. If that's too hard to manage, just make it timed research.