Thanks for asking! I joined the Baha'i faith relatively recently (2 to 3 years ago) after I had been an agnostic most of my life. What attracted me most was that it's very progressive, basically "secular humanism plus God"... and that all the Baha'i I met were, without exception, really wonderful people.
We believe in a single, one and only God and unity: Unity of God, of mankind and unity of the prophets. We acknowledge all Biblical prophets as divine prophets, as well as Jesus, Mohammed, Buddha, Krishna and a few others -- but Baha'u'llah, who founded the Baha'i religion in 19th century Persia, was the most recent prophet. We call that "progressive revelation": Every couple of centuries, God sends a new messenger to "update" religion, for that it best suits the needs of mankind in its respective stage of development. Judaism, Christianity, Islam, Buddhism, Hinduism and so on are all true religions, but the Baha'i faith is the most recent "update" and thus best suited for our times. But it's not the last either: In ca. 850 years, another prophet is expected to appear to reveal another "update".
The Baha'i religion came into existence in 19th century Persia in a Muslim background, and maybe has the same relation towards Islam as Christianity has towards the Jewish religion. You may also recognize a few elements of Sufiism in the Baha'i faith. All scriptures written by Baha'u'llah are considered holy by us, as well as the scriptures by his son Abdul-Baha, who plays a similar role for Baha'i as Paul plays for Christians. The forerunner of the Baha'i faith was the Bab, who plays a similar role as John the Baptist for Christians.
A clergy is explicitly forbidden in our faith, as no believer is above another and we value independent search for the truth. Baha'u'llah determined that all institutions of our religion are democratically elected by the believers. That is why in our devotion meetings, there are no preachings or collective prayers, but just meditation and individual prayers. The holy scriptures say that any religious conviction that contradicts science is mere superstition. Zealotry, aggressive prozelytism, religious bigotry and "holy war" are explicitly forbidden in the scripture. We are commanded to accept the believer of any other religion and living in peace with them, and merely using the word as a weapon. Badmouthing other people behind their backs is considered a sin.
Also, we believe it's our goal to peacefully work for the goal of uniting mankind, just like it once was the mission of Moses to unite the tribe and of Mohammed to unite nations. Our long term goal is achieving a peaceful community of the entire mankind, even if that will still take a long time. Shoghi Effendi, great-grandson of Baha'u'llah and Protector of the faith until 1957, said the "three greatest tin god idols" people are worshipping these days instead of God, are racism, nationalism and communism. Baha'u'llah said the best form of government for the time being is a combination of republic and monarchy, as in the UK. Also, before mankind has grown into one, institutions of collective security are the best way to deal with international problems.
We also believe in an eternal soul, which will continue to exist forever in the afterlife. Heaven and hell are just symbols for being close to are far from God in the next life.