[Goose]

A very informative thread on the S-500 system, basically an upgraded version of the S-300V system. 
The S-500 is not a derivative of the S-400 system, which is itself derived from the S-300P/F system. As shown recently the S-400 does not seem to be able to defend itself from ATACMS, a short range ballistic missile, and this is not too surprising as it's main role was to defend against slower air breathing threats such as planes and cruise missiles.

Yes and no. The Patriot was originally designed and built to operate against air-breathing threats as well. It didn't stay that way however, interestingly enough possibly for political reasons. The USAF could and did argue the US Army didn't need Patriots because the USAF would take down all the air-breathers. Originally Patriot, as a point defense weapon, was justified as a weapon to take out "leakers". That argument didn't justify building lots of expensive missile systems, so the ABM capability became the raison d'être for Patriot. As a bonus, it actually worked (sort of :-)! Supposedly the S-400 was going down the same path, according to its developers. It has a lot of modifications to give it ABM capability. How well they work is still TBD. No inherent reasons I know of that it couldn't.

The S-500 was recently deployed to Crimea per Ukrainian GUR head Kyrylo Budanov to protect the Kerch bridge. This is the first time it has been deployed, and Russia probably only has one operational system. It should be their best ballistic missile defense system, however it seems very liable to being overwhelmed with even a small number of missiles as the thread explains.

https://x.com/NOELreports/status/1800981129966563744
https://x.com/John_A_Ridge/status/1801322095185375647

Some points not mentioned so far is that the first of anything, Russian or US, usually doesn't work very well. First, it takes time, sometimes lots of time, to fix the deficiencies. Sometimes  it isn't possible to fix it. Second extensive pre-deployment testing is essential to having any chance to deliver a first article that "works". Testing ABM systems is at best very, very expensive. You need a target and you need a "realistic" scenario and geometry. The US is pretty good at this. Russia, not so much. On top of that the contractor really really wants the first article to get accepted. If your DOD is corrupt, it can be a lot easier to "pass" the tests. Even in the US the desire to protect a program's budget can lead to some collusive "funny business".

Patriot worked pretty well in its first operational use against SCUDs. How well is still classified. Probably Patriot worked better than its detractors said and worse than its fans said. In the interim, there have been lots of "lessons learned" and both hardware and software upgrades. It is safe to say it works very well at this point. Of course, the new radars will make it work much better :-).

[Goose]

A very informative thread on the S-500 system, basically an upgraded version of the S-300V system. 
The S-500 is not a derivative of the S-400 system, which is itself derived from the S-300P/F system. As shown recently the S-400 does not seem to be able to defend itself from ATACMS, a short range ballistic missile, and this is not too surprising as it's main role was to defend against slower air breathing threats such as planes and cruise missiles.

Yes and no. The Patriot was originally designed and built to operate against air-breathing threats as well. It didn't stay that way however, interestingly enough possibly for political reasons. The USAF could and did argue the US Army didn't need Patriots because the USAF would take down all the air-breathers. Originally Patriot, as a point defense weapon, was justified as a weapon to take out "leakers". That argument didn't justify building lots of expensive missile systems, so the ABM capability became the raison d'être for Patriot. As a bonus, it actually worked (sort of :-)! Supposedly the S-400 was going down the same path, according to its developers. It has a lot of modifications to give it ABM capability. How well they work is still TBD. No inherent reasons I know of that it couldn't.

The S-500 was recently deployed to Crimea per Ukrainian GUR head Kyrylo Budanov to protect the Kerch bridge. This is the first time it has been deployed, and Russia probably only has one operational system. It should be their best ballistic missile defense system, however it seems very liable to being overwhelmed with even a small number of missiles as the thread explains.

https://x.com/NOELreports/status/1800981129966563744
https://x.com/John_A_Ridge/status/1801322095185375647

Some points not mentioned so far is that the first of anything, Russian or US, usually doesn't work very well. First, it takes time, sometimes lots of time, to fix the deficiencies. Sometimes  it isn't possible to fix it. Second extensive pre-deployment testing is essential to having any chance to deliver a first article that "works". Testing ABM systems is at best very, very expensive. You need a target and you need a "realistic" scenario and geometry. The US is pretty good at this. Russia, not so much. On top of that the contractor really really wants the first article to get accepted. If your DOD is corrupt, it can be a lot easier to "pass" the tests. Even in the US the desire to protect a program's budget can lead to some collusive "funny business".

Patriot worked pretty well in its first operational use against SCUDs. How well is still classified. Probably Patriot worked better than its detractors said and worse than its fans said. In the interim, there have been lots of "lessons learned" and both hardware and software upgrades. It is safe to say it works very well at this point. Of course, the new radars will make it work much better :-).