Taxi drivers in Rome, taken as a whole, are no better and no worse than taxi drivers in any major city. Most of them will take you to your destination by the fastest route (which may not be the shortest) and will charge the price shown on the meter plus permitted extra charges of €1 for each bag after the first in the luggage area and €1 for each passenger after the fourth.

Take care to always use an official taxi, licenced by the City of Rome. They are white, with a "TAXI" sign on the roof and the Rome crest (with "SPQR") on the doors. They have a meter, which should always be used unless you are travelling between central Rome (Aurelian walls), main train stations and one of the two airports (Fiumicino and Ciampino). Look to be certain it is being used.

Fixed price to airports. There is a fixed price from central Rome (within the old walls, called Aurelian walls) to the airports and vice versa: €48 for Fiumicino and €30 for Ciampino, including luggage. Don't use "City of Fiumicino" official taxi at Fiumicino airport to go to central Rome: you'll pay a fixed price of €60 (instead of €48).  If you are travelling between an airport and somewhere outside the old walls (excepted other specific destinations like train stations) normal metered charges apply. The most recent link to check for the current prices is here:

Many complaints about rip-offs arise from someone using a vehicle that is not an official taxi. Ignore touts who may approach you at an airport or train station, offering a "taxi" service. Follow the signs to the taxi rank, and use an official taxi.

Even with the meter, a few drivers may try to rip you off. You may allow a euro per bag, but otherwise they should go by the meter. Make a note of the taxi number plate so that you can report any problem by a complaint form. Misunderstandings can arise over payment, especially as tourists may be unfamiliar with euro currency. Have small change and count it out slowly as you pay, as they have been known to switch your 50 for a 10 (similar color) and claim that is what you gave him. Report them if there are problems. Have one person stay in car while the other watches luggage loading/unloading. However, most tourists have no problems with the taxi drivers.

Tipping: It is not necessary to tip for anything in Italy. However, it is customary to round up taxi fares to a convenient amount.