It's a good meter. As mentioned in the last thread I saw discussing it, the Keithley 6.5 digit most current model probably has a bit of an edge in terms of UI and remote functionality, but the 34461 is a solid meter, I've been happy with mine. If you're coming from a meter with no fancy screen it makes a big difference for change over time sorts of things (measuring tempcos and whatnot), because being able to have the data plotted out on a graph is a really great feature.
There was that little thing with the 1kV input rating that, if I remember right, turned out to be a false alarm? It takes a second to boot, but it's not crazy long, and it's plenty responsive in normal use.
Not sure what you mean by ecosystem..... it's most easily integrated with other Keysight gear, but it's got your standard front panel and remote operation features and interfaces, so it can play nice with a lot of stuff.