Here are some highlights:
1) The presentation quality was extremely high. Check out the program: http://www.sefs2013.de/.
2) The venue was amazingly posh, with comfortable lodging, easy to navigate session rooms, and very good food. Check out the Movenpick Hotel: http://www.moevenpick-hotels.com/en/europe/germany/muenster/hotel-muenster/overview/.
3) The conference was a really nice size. It was smaller than what I've attended the last few years, which meant that it had fewer concurrent sessions and I didn't have to jump between sessions that often.
4) The diversity of plenary talks was excellent. They had a really nice balance of early-career, middle-career, and late-career speakers, male and female speakers, speakers with different disciplinary expertise, and speakers from different countries. Here they are: Simona Bacchereti, Emily S. Bernhardt, Ulrich Brose, Claudia Dziallas, Carol Eunmi Lee, Judit Padisák, Robert W. Sterner, and Diego Tonolla.
5) My oral presentation was titled A conceptual framework for understanding multi-scaled cause-effect relationships between terrestrial and aquatic ecosystems and it was in the special session titled Organic carbon and nutrient dynamics in freshwaters under global change. The room was completely full during my talk and it was well-received.
6) The city of Munster was really nice - see pix below. It is dubbed the bicycle capital of Germany, and the people there are proud that they have not had a mugging in over 20 years. The Movenpick was right near a beautiful park with a nice-sized lake that was surrounded by trails (middle pic below), as well being walking distance to the Botanic Garden (map here: http://goo.gl/maps/dD6DG).
My only real disappointment was that the majority of attendees study moving, rather than still, water (i.e., rivers and streams rather than lakes and ponds), but there were certainly enough interesting presentations for me to learn from and I was happy to start the year at SEFS.