Mlinzi is a phenomenal sentry. It will not kill the runner, in most cases, but facecheking it will give the runner a big hit. Usually, the runner will choose to burn cards from the stack and take one net damage. For a total loss of 1 card in hand and 7 cards in the deck. 7 cards, in a 45 cards standard deck, mean 15% of the runner deck. That is a lot of combo cards loss. While it does not affect the tempo, it will affect the econ of the runner.
Worse, if your corp is grinding the runner, like Jinteki Personal Evolution, the runner will soon find themselves out of cards to interact with agendas.
And, at 7 creds to rez, it is 1 cred cheaper than the other big sentry : Anansi.
So, how does it compare to Anansi? It compares well, but is Mlinzi is a bit more specialized. Mlinzi is good if you want good strenght to rez ration, because you are aiming to tax the cred of the runner for the least amount of creds spent. Mlinzi is also good if you have a grinding plan for your corp (Jinteki PE, Weyland Builder of Nation, Obotaka Protocol, ambushes assets and agendas, etc.)
But in general Anansi will be better, because at the end game, a runner can just lose their stack and pass Mlinzi for free. Boomerang will make Mlinzi trivial to pass (only one net damage). Any bypass will work. With Anansi, Boomerang is useless and bypass cost 3 net damage.
So, Mlinzi is more specialized, but cost 1 influence less and 1 cred less. Fair trade for a more specialized ice. Mlinzi should be played more often, it has a place in many achetypes and a good fit for Jinteki.
Mlinzi can't be passed for free with an empty stack; if you can't trash cards from the stack, you have to take the damage. So it actually has quite some blocking power in grinder decks, making it pretty good there.— callforjudgement