There are of course a variability in the competitiveness level of different offices within the Firm. For examples, offices in global hubs such as London, Singapore, HK, NY, San Francisco, are really in high demand.
In average though, the chances of getting in are still equally difficult if we compared to other companies in each regions / countries.
Moreover, in some countries, ability to speak local languages and familiarity with the local culture ('how things work here?') is expected, as consulting relies on trust-based relationship with clients.
Hope it helps.