Though I'm not yet a convert, I'll post a few things:
1. Theosis-ever so much. The idea that we're not just worshipping God and Jesus as some kind of cosmic fire insurance against Hell, but that through our faith and prayer and living and by His grace we may enter glorious union with Him, be transfigured, sanctified and made radiant.
2. On that note, mysticism, and the fact that the Orthodox Church makes room for contemplatives like me who are often somewhat marginalized by modern American Christianity.
3. Liturgical languages-perhaps a more Biblical interpretation of "speaking in tongues". I'm a total language geek anyway, and while I know God hears us in every language, I love hearing and participating in prayer and worship through the diversity of human tongues.
4. Community that is focused on recreating as best as humanly possible the Way of life and worship according to Jesus Himself.
5. (on a slightly smaller note), this prayer:
Lord, bless those who praise You and sanctify those who trust in You. Save Your people and bless Your inheritance. Protect the whole body of Your Church. Sanctify those who love the beauty of Your house. Glorify them in return by Your divine power, and do not forsake us who hope in You. Grant peace to Your world, to Your churches, to the clergy, to those in public service, to the armed forces, and to all Your people. For every good and perfect gift is from above, coming from You, the Father of lights. To You we give glory, thanksgiving, and worship, to the Father and the Son and the Holy Spirit, now and forever and to the ages of ages.