Umbrella is a cool card but having now existed for a few years, it doesn't seem to be that strong.
It doesn't typically find a home in anarch decks, even though you might think it could. Anarchs that install Botulus usually use Botulus to break the ice, and Umbrella would be superfluous. If the Botulus can't fully break the ice, you could play Poison Vial instead which has a lot of extra utility, against bioroids like Bran 1.0 for example. You might imagine that using Chisel with Umbrella is decent, but in practice I've never seen that work well.
Umbrella really only makes sense in Arissana Rocha Nahu: Street Artist decks, because for other runners it can be very clunky to get all the trojans in the right place to use umbrella to break ice and make a successful run.
As of Elevation release, many players are cold on Arissana Rocha Nahu: Street Artist because Madani might arguably just be better, having fewer restrictions and being usable on the corp's turn as well.
However, I think the main reason that Umbrella is weak is because of the text:
If at least one subroutine was broken this way, each player may draw a card.
On the face of it, one might think this is equally beneficial to the runner and the corp. However, I think actually, letting the corp draw a card on the runner's turn is more beneficial for the corp than the runner.
- If the runner is running HQ and this happens, it may dilute agendas held in hand and help protect the corp if the runner does access HQ.
- Many corp cards now require the corp to trash a card. So for example, using Umbrella to break one ice may provide fuel for cards like Anoetic Void or Boto
- It's generally harder for corps to draw cards than runners, especially with the rotation of Rashida Jaheem. Runners generally have lots of draw engines like Diesel, Dr. Nuka Vrolyck, The Class Act, Verbal Plasticity, which are played in many decks. Runners usually try to get more than one card drawn per click. Corps typically don't or can't do this nowadays -- there is Predictive Planogram but it's more often used for credits than draw. Red level clearance exists but isn't widely played. There are not too many assets that draw cards either.
Some corps like AU Co.: The Gold Standard in Clones and The Zwicky Group: Invisible Hands have built-in draw and then perhaps this argument doesn't apply. But typically, when I'm playing as a corp and the runner breaks something with Umbrella, my position in the game is improved by both me and the runner drawing a card during a run.
It may be as simple as:
If the runner draws a card with Umbrella, they are already running. And so even if the card is good, they probably can't play it right now, and don't have the benefit of planning their turn around this card. They might only have one click after this run ends, and this new card probably won't have impact until the runner's next turn. On the other hand, as the corp, when I draw on the runners turn I will start my next turn with extra cards -- starting with 6 cards is likely to lead to me having a much better and more impactful turn than I would otherwise. And the impact of this draw is likely going to happen for the corp before it happens for the runner.
It's not easy to measure, but having played enough games against players that use Umbrella, I find that it "brings me joy" as the corp to see the runner install Umbrella, and when they break something and we both draw a card, it usually feels to me like I'm getting a significant advantage. Make of that what you will.
I think it's totally fine to use this on central servers turn 1. Especially to defend HQ before even drawing your first agenda. Yes, it will probably trash itself at some later point, but until then, it provides a cheap and efficient tax. Certainly not the ideal use case, but not that terrible either.
— Krams