I feel like I need to vent this out. As the event passed by, people have already noticed that "submarine" makes this event a lot easier.
A well-prepared base with submarine fleet will save you a lot of time. This is the case for E-1, where you can sub-cheese (submarine-only fleet) through the map as the map is similar to a combination of 2-3 and 1-6. It also allows you to farm E-1 for submarines (albeit the RNG) as the map is really easy even without a submarine fleet.
For E-2, it's a simple transportation map. The map itself is tedious, yet it isn't horrible to the point of unbeatable. The node itself makes up for most of the map's difficulty, being difficult to reach the boss through Transport, Surface, or Carrier Combined Fleet and is horrible for Transport Combined Fleet in Final form. The boss, however, is not too painstaking as you do not need to sink her and the map only becomes harder during final form due to the appearance of Ancient DD Hime. Yet, it's nothing compared to the mess of E-3.
E-3 HP Bar and the boss section itself, are not bad. Actually, they executed it decently. The convoluted Debuff was made simpler (after multiple experiences with it since Summer 2016) as it only requires you to S-rank the two most notable (CA Hime and Isolated Hime) sub-bosses around the map. This makes it easier to guess compared to the previous events. Even the 2nd Starting Point was made obvious by just clearing the TP-phase. But yes, that is the worst part....the TP-phase.
I think we can all agree, hands down, that the worst part of this event (unless you cleared it in one run) is the TP-phase of E-3M/H. A ridiculous (yet reasonable) request was made where you must scrap a Recon plane to convert your Saiun to a portable version to carry it on your SSV. To top it off, you need two of it to clear the map. The worst part is that if you didn't manage to at least A-rank the boss, you lose your portable Saiun and need to get them again. This made people wasted countless of resources and development materials just to get those Saiun (and Recon planes).
But how is this the bad? Didn't devs warn us about Saiun? Didn't they told us to prepare at least 2 Saiun? Why the hate? Well....the hate came from HOW they told us. Here is the tweet in question:
@KanColle_STAFF
Pre Update
To Admirals who are planning on entering the Winter 2017 Event: 【Operation 'Hikari', the Emergency Deployment of the Reconnaissance Force!】 in Medium or Hard difficulty: For the latter half of the Operation, you will be required to bring several numbers of the Reconnaissance Aircraft, Saiun. Along with your equipment prepared for the Event, please also prepare at least 2 Saiun in your arsenal.
冬イベント2017：期間限定海域【偵察戦力緊急展開！「光」作戦】で、【乙】作戦、または【甲】作戦に挑戦される提督の皆さんへ。 同作戦の後半では、複数の艦上偵察機「彩雲」が必要です。作戦に投入する艦隊戦力の装備の他に、二つ以上の「彩雲」の準備をお願いできますと幸いです。
Devs are well known to be cryptic in their hints in twitter but nothing comes close to this one. From this tweet, we know that we are required to prepare Saiun, correct? The problem is, even though some might have speculated it, not many expects those Saiuns to be "consumed". Speculations are "high LoS is needed in E-3" more than "Saiun will be consumed". Frontliners had it worse as they need to test out the maps and the LoS-check causing them to lose more Saiuns than others. Thus, not many are prepared to spent this many Saiuns/Recon-planes/Devmats and many went broke. This came from just one tweet, that didn't care to specify enough on why it is important to have those Saiun.
Note: You can say that it is possible to speculate considering the purpose of the operation.