As far as my travels around India are concerned, the city of Patna is one place that I don't have very fond memories of. I have images of a dusty, polluted city in my mind, and, above all, images of guesthouses that it's very expensive to spend the night at.
I advise travelers visiting the Ganges Valley not to stop off at Patna, but to head straight to Varanasi (aka Benares) instead. That city is a much better place in which to experience all the cultural riches the area around this sacred river has to offer.
Bihar is one of the poorest states in the whole country; and I could really detect this poverty in Patna, where there seemed to be even larger numbers of beggars than there are elsewhere, in other large Indian cities … which is really saying something.
Patna istypical of many Indian towns : noisy, chaotic, dirty, but the frenzy is still fascinating. You will be told to be on your guard if you are planning to go there during your trip to India, bearing in mind the poor economic and social conditions in which people live. Personally, I found the locals to be very welcoming and respectful. As the town is not that touristy you'll feel less harassed by vendors, taxi drivers and guides.
Things to do include dolphin watching, visiting the Gurudwara Akal Takht Sri Patna Sahib Sikh temple and...what else? There's not really much for tourists to do, other than maybe use it as a place to catch a train going elsewhere. At the same time I have to say that we ate really, really well!