Turbo itself doesn't have a lot to offer, and it's primary interest to travellers is its role as the place to get a boat to Capurganá, from where it is possible to get a boat to Puerto Obaldia in Panama.
The city itself has a population of just under 50,000, so there is stuff going on if you do decide to spend a few days here. There is a main plaza in the center of Turbo (Calle 100 and Carrera 13) and most of the shops and restaurants are within a few minutes walk of the plaza.
The docks where the boats leave from is just over the bridge from the main plaza, although you can find it just by following the smell; the water around the docks is a fetid, putrid mass of sludge that almost seems alive as it bubbles with the methane given off by decaying sewage.
More information on Turbo can be found on the city's government website : http://www.turbo-antioquia.gov.co/
Turbo is on the Pan-American highway, and there are regular buses here from Medellin. The ride from Medellin takes about 8 hours and costs 55,000 COP, but beware as the road is one of the worst main highways in Colombia, with frequent breaks in it due to landslides and much of it is untarmacked.
Fast boats to Turbo depart from Capurganá, further along the coast. There is somewhat of a monopoly here, which is a bit annoying if you are trying to enter Colombia on the cheap. The fare is COP$ 50,000, they also charge excess baggage at COP$ 500 per kilo over 10kg. Everything is weighed.
It is very easy to get around.
Turbo has a beach (admittedly not a particularly nice one), about 15 minutes walk from the main plaza, crossing over a concrete bridge that affords a nice view of the surrounding mangrove swamps. If you don´t fancy the walk, there is a bus service, or you can get a taxi or motorcycle. There are a couple of nice bars on the beach, which faces west, so it's a great place to go and watch the sun set.
In addition to the above, there are a range of cheap hotels, just opposite the docks where the boats leave from :
Tickets for the boats go on sale from about 6am, with boats leaving up until just before midday; it´s advisable to get a ticket as early as possible to be certain of getting a place however.
The main operator seems to be Cootransflumar (872 9280).
A ticket to Capurganá costs 49,000 COP, although be aware that you will also be required to pay 1,000 COP for every 2 kilos of luggage that you take when you board the boat (not always enforced). The ride to Capurganá is 3 hours of worth of concussion-inducing bumps as the launch jumps the waves, so be prepared before you go. You and your stuff are also likely to get wet, so take appropriate precautions (although large plastic bags are available for sale on the docks). It's best to book your ticket the day before so your name is called early as they load the boat. Try to get a seat in the back on the port side of the boat for a more comfortable and drier ride. You can also tip one of the luggage boys to save you a good seat. It's worth it. You might also want to have rain gear ready.
If you miss the boat to Capurgana in the morning, there is another boat that leaves later to Acandi (35,000 COP), from which you can catch an additional boat to Capurgana in the afternoon (15,000 COP).