Pluspunten
From the perspective of a scientist / postdoc: Really diverse scientific environment, plenty of collaboration opportunities within and without Charite, several other biomedical institutes in Berlin, including two Max Planck Institutes, the Max Delbrück Institute, Robert Koch Institute and others. Everywhere there are bright scientists, both PIs and students. Working at Charite is really interesting for a scientist. Salary, as usual at such institutions in Germany is predetermined according to your salary category and years of experience, no surprises here, either bad or good. Berlin: great public transport, great atmosphere, great culture.
Minpunten
Charite is really huge, so I am not trying to blame the administration, plenty of them are working hard. However, going through official channels to buy a laptop or even a paper notebook can be incredibly frustrating. Same with conferences, travels, books, lab equipment, consumables etc.etc. Everything takes a lot of time and requires a lot of effort on your part, esp. filling out puzzling forms, mostly in German and using weird internal IT systems or, at best, SAP. Some obstacles remain insurmountable. You have to participate in mandatory online trainings aimed mostly at nurses and technical staff, and mostly in German. In general, unlike at pure research institutions, ability to speak German is much more important here. Internet access and usage is severly restricted (again, forms, forms, forms), mostly because of the tons of sensitive patient data, but annoying nonetheless. A lot of the IT infrastructure is obsolete, or in a semi-working condition. The intranet pages are a horror. Getting a permanent position is unlikely. PI's are usually older white male Germans. Some of them can be really full of themselves. Living in Berlin can be quite expensive, especially renting an appartment within a reasonable commuting time. Charite itself is not one campus, but multiple sites spread throughout whole Berlin, so depending on where you work you may have a very different experience of living.