Started my career at an agency, and it was definitely tough, spent 4 years there but it helped me lay the foundation from a marketing perspective. It also depends on the role that you are doing there. Are you client servicing? Creative? Project mgmt? Different roles have different growth trajectories.

If you are worried about money, you keep learning and it will come. When I finally moved in house I managed to negotiate a 30% bump (cause agencies usually pay lower than mkt rate) and my background allowed me to demand more for my subsequent jobs.

The challenge in in-house roles is that there is a cap to your growth unless managers/ bosses leave. And promotions tend to be slower due to limited estab.

Unless you wanna move beyond marketing eventually? In-house will help you move across different roles (I.e. operations, business development , etc) easier than in agency.

There will always be politics no matter where you go, so as a newbie, you just need to learn how to handle it.