I was incredibly excited when I started thinking about going to Ireland (and the rest of Europe) for a full semester, and despite the minor annoyance of paperwork, I finished it all and got ready for my semester abroad. Going back to school about 15 days early was discouraging at first, but once again, it was well worth it. We had orientation within the first few days of being there, and it was similar to the first day of college again: everyone was friendly and welcoming and wanted to get to know and hang out with each other.
The first few days or even weeks were mostly spent meeting other foreigners who were new to the university, which included many Americans and European Erasmus students, among others. After a few classes, people would feel more comfortable and hang out with locals, and those Europeans, Americans, and students from all other countries and continents who had been around a bit longer. Traveling around Europe was relatively simple (especially after a few trips), and very cheap compared to in the US. Weekend trips became the norm: meeting people in hostels, going places only seen in travel books with friends.
Study abroad was possibly the best decision I have made so far, meeting and befriending people from all over Ireland, all over Europe, and all over the world. After I finished exams, I backpacked around Europe, flying into Berlin, visiting various places and people (staying at multiple friends' houses for free, and even experiencing each culture firsthand with family dinners) and out of Bologna almost 3 weeks later (not even nearly as long as trips that some friends had taken). After half of a year, I still correspond with most of my old classmates from the semester, and just got back from visiting a group of them at their school in Los Angeles. Many, if not most, of the students that I studied with have become (hopefully) lifelong friends. Especially with the help of Facebook and even Skype, which greatly aid communication for users, you can talk to, and set up dates to visit your foreign friends.
Studying in Europe for a semester opened my eyes to travel, allowing me to go more places in a shorter time than I would possibly ever be able to do otherwise (other than potentially in retirement). Travel had been something that I had enjoyed, but has since become a major priority in my life. My best suggestion for any student in college is to study abroad, even if they had never even considered it.