A "pre-emptive replacement" is a somewhat strange thing. Normally, you delay replacing something until the old one has stopped working to avoid overlap. Yet, Living Mural is perhaps best thought of as a pre-emptive replacement for a card the designers knew would rotate very soon: Ika. The problem with pre-emptive replacements is that they can look strange when first released, as they might not see any play for some time while the old options remain.
In the spirit of prescience, I'd like to make some predictions and speculations about what might happen when Ika does rotate, and Living Mural is forced to step up to the plate as the premier Trojan Killer.
The Differences:
Higher install cost 3 vs 0
Breaks less efficiently 1 credit per subroutine vs 1 credit for 2 subroutines
Pumps marginally more efficiently 1 credit for 2 strength vs 2 credits for 3 strength
Lower base strength 1 vs 2
Threat 4 text makes it 4 strength for a single turn
Different Interface requirements (see below)
From a pure numbers standpoint, it's looking weaker, except for ICE which has exactly 3 strength or ICE with 6 or more strength, Ika can interface more efficiently. ICE with 6 or more strength constitutes a painfully short list, whether it's been released by NSG (Trebuchet, Cloud Eater, Tyr and Colossus (who I consider an honourary member)), or whether it's an old FFG card that will be rotating with Ika (SYNC BRE, NEXT Diamond, Hydra, Archer and Surveyor). Even against 3 and 6+ strength ICE, Living Mural often doesn't break them as efficiently due to its lower subroutine cost-to-ratio. And even then that's without factoring in the higher install cost.
At Threat 4, this becomes somewhat more favourable, as you can now break anything with 4 or less strength without pumping and break almost everything with minimal pumping. If you can continually bounce this card with UAV, an argument can be made that it is always a 4-strength Icebreaker once Threat 4 is achieved. The problem is that Threat 4 tends to be deceptively late into the game, especially compared to Threat 3, and having to continually bounce and pay for Living Mural to stretch the benefits means this is meagre compensation for all the other sacrifices this card makes during the rest of the game.
Not only that but since it already pumps rather efficiently, 3 extra starting strength actually saves you fewer credits than you might think (usually only 1 or 2 fewer credits per ICE, and that's assuming it's a large ICE, which tends to have more subroutines anyway), which makes it hard to justify bouncing and paying the reinstall cost. Furthermore, it doesn't compensate for the fact that it still breaks subroutines 1 for 1, which is one of the major downsides this card has compared to Ika, especially against Sentries which frequently have multiple subroutines.
The last and perhaps most interesting distinction is its mobility, where Ika could be used to break any ICE anywhere, for the additional movement cost, Living Mural can break anything in the same server, but cannot be moved. This is somewhat reminiscent of the old Cyber-Cypher in its high efficiency compared to conventional breakers, limited by only being able to affect a single server. Here Living Mural can eke out some efficiency against tall Glacial servers that include multiple Sentries that Ika would otherwise have to continually bounce between. However, if you want to break sentries on multiple different servers in the same turn (such as for Deep Dive which Arissana often uses), you will either need to have multiple Living Mural's installed or use Spree to move it mid-turn.
On the whole, the comparison is not looking great, maybe this card is better against breaking multiple high-strength sentries stacked on top of the same server once Threat 4 is reached but who are we kidding, there's a very good reason that every Arissana deck I've seen runs Ika and not Living Mural. Perhaps the real question is if Arissana will use Living Mural at all, once Ika rotates or fall back on conventional breakers like Echelon or even import a breaker like Revolver or Carmen?
Well, let's compare it to Carmen, the bread-and-butter Killer from System Gateway.
From a strength perspective, Carmen is eerily reminiscent of Ika, with 2 base strength and pumps 2 for 3, which means that like with Ika, Living Mural is cheaper at pumping when it comes to 3 strength and 6 or higher strength ICE. However, as they both break 1 for 1, it can actually retain the added value and is better against 3-strength ICE while being competitive against 4 and 5-strength ICE too, unlike with Ika. And if you can reliably get the Threat 4 ability online, you can break substantially more efficiently than Carmen, while having comparable install costs (you can usually install Carmen for 3). Once again, however, the server limitation is its downfall, as Ika could move anywhere for a cost, and Carmen, like most conventional icebreakers can break any sentry anywhere without problems. Living Mural's one server limitation becomes crippling and I struggle to see how Living Mural could coexist with Deep Dive decks unless you add Spree, or include multiple copies of Living Mural, ultimately just adding to the setup and expenditure, and driving down its value proposition in the process.
Alternatively, however, cutting Deep Dive and adding more conventional multi-access such as Conduit and “Pretty” Mary da Silva (or importing a strong card like The Twinning), or even utilizing some Flux Capacitor + Cataloguer combo, while putting a Living Mural on R&D and regularly running R&D to lock the Corp could be a viable strategy. Or you could place one of these on the scoring remote to lock the Corp out of scoring and force agendas to accumulate in HQ before going in for a Spree + Cupellation run to win the game.
Ultimately, it's a very different icebreaker compared to Ika, with very different strengths, weaknesses and limitations. While it is almost certainly weaker and more limiting than Ika on the whole, it will be interesting to see what becomes of Arissana decks once Ika rotates. Will her playstyle change to fall in line with Living Mural's as she focuses on a single server or will she stop using Killers altogether and rely more heavily on Slap Vandal + Poison Vial combos, or turn to Botulus and Physarum Entangler or will she prefer to use more conventional non-Trojan Icebreakers like Carmen or Echelon to be the backbone of her deck while using Trojans like Pichação and Hush as more of an extra flourish? No one knows for sure, but it will be interesting to see.
Thematically Living Mural pretty much sells itself, the server is an alleyway and the Mural is a painted-on, living weapon that can attack anything in its path, but cannot move itself. It's very in theme with Arissana's identity as a street artist and Urban Art Connoisseur and fits perfectly with her whole character design. As for the actual text on the walls; "Mente" literally translates to mind or maybe in context mental? Perhaps calling NBN mental or mad? The text on the other side of the wall seems to read "viva livre brega" which roughly translates as live, free, strange (or quirky perhaps). I'm not really sure what that's supposed to mean and I think I either read it wrong or translated it wrong, corrections would be much appreciated! Similarly, the word in the top corner of the left wall seems to read "fora" if you squint, which means outside, what that means in context and the accuracy of my reading is questionable, to say the least, and I'd love to see a full size, high-quality copy of this art just to understand the little references and world-building details better. Lastly, including an Archer walking past and getting tongue-slapped is just a really nice touch to tie the whole card together, a true weapon, worthy of the Killer name! (yet so cute!)
TLDR: A weaker replacement for Ika in Trojan-based Arissana decks, doesn't see much play at the time of writing but if you are reading this after Dawn that may well have changed dramatically.