You'll find that you're on the same wavelength. Conversation will flow; your ideas will come out in a tumbling rush. You'll agree on many things, and even when you disagree it will be interesting, because you'll get to look at both sides of an issue together and debate them.
You think in similar ways; your thought processes take similar tracks, ones that each of you will recognize in the other. Your individual reasoning styles and the ways you process information will blend together nicely, so you'll share a feeling of familiarity. You'll enjoy discussing things together, both to hear yourselves talk as well as to get your buddy's take on things. Your love of talk and that quick mental connection will enhance your social life together. Your connection could even be more mental than emotional. You should both try to dig deep in your conversations, as your inclination might be to stay on a superficial level.