Yes absolutely. We leave the filter in. The coffee doesn't linger and definitely doesn't become bitter. We often tried it with trained coffee experts. The coffee in the filter even keeps your favorite drink hotter for a lot longer than if you take it out.
The aromas of the coffee take about 4 minutes to release. Then we give it a few more minutes of rest and time to cool down. I find that after about 12 minutes it has the right temperature and fullness to enjoy.
Perfect for a long breakfast!