Wouldn’t say “very successful” when you lose up to 10-15% of your invading force (deaths + wounded).
Wounded troops don't necessarily qualify as losses since even the slightest scuff is classified and registered as a wound. In effect most of those wounded will return to duty in a matter of minutes or hours.
As for Russian casualty figures, I wouldn't place trust in Ukrainian and western sources at all. It is obvious that these have embarked on a gigantic propaganda campaign where facts no longer matter and psychological conditioning is everything. The fact that they need to resort to such unusual degrees of censorship is further evidence of this.
To my knowledge Russia hasn't published new numbers since March 1, when it reported less than 500 KIA and less than 1600 wounded. Assuming their casualty rate has remained constant (which is not certain), the current number would be around 1500 KIA and some 5000 wounded. If estimates that the Russian invading force consists of 100.000-200.000 troops are accurate, it would mean their losses amount to between 0.75% and 1.5% killed, and about 3% to 6% killed or wounded.
Even if Russia ultimately loses 15000 men (killed) or more taking over or completely neutralizing a country the size of Ukraine with the powerful backers Kiev has, it'd remain within logical expectations.
If the roles were reserved and Iran had caused 7,000 US casualties and Iran had not lost a single major city (Kermanshahr would be our Mariupol and let’s Tabriz and Mashhad our Sumy and Karkhiv). I would say that would be a major win for us.
If the US regime believes it can afford the 7000 casualties, then Iran will not have made a gain. In war, win or loss is determined by whether previously defined political aims intended to be served by the military instrument are met or not. As well as the long term social and political consequences of the war effort.
The US reaching its war objectives like Russia is bound to, would spell doom for Iran. Iran cannot afford but to make any kind of game-changing military action unaffordable for the Americans and deter them effectively from such undertakings, like she has successfully been doing to date.
The issue isn’t wether or not Russia can take land, of course it can. It has the military power to crush Ukraine that is not in question. The question is does it have the time, because we know as conflicts rage over time stagnation happens (Yemen, Syria, Libya, etc).
It depends on the conflict, I'd say. Especially when it comes to this conflict since as mentioned, Russia has not taken the gloves off and is extremely wary of inflicting too much collateral damage (both to Ukrainian and especially Russian-speaking civilians, as well as to infrastructure) when compared to the average NATO campaign.
If Russia doesn’t care about “costs” then this could be cateoegized as a successful military operation.
Economic costs are one thing, but how much human costs a country can afford is a function of its own social tolerance for casualties, as well as of the objective availability of manpower. A third criterion would be whether the losses are worth it considering the underlying political goal to be achieved. Tolerance is higher in Russia than in the west, and manpower is abundant enough. Russia's performance in terms of casualties should be gauged based on its own tolerance / resource levels.
As for whether it's politically worth it for Russia, the alternative - being encircled by NATO on its western borders, might well have heavier consequences in the long term.
But I think even if Russia wins it will be the whole world talking about the ineptitude of the Russia war machine at doing even the “basics” they teach in military academy.
I think this will be limited to the western world and its client states. So far I haven't heard western narratives being echoed in truly independent nations, and I'm not sure that they will adopt them.
