Perhaps not surprisingly in this increasingly high-tech world, new technologies are being developed all the time. The accuracy of some units is really quite good and will get better. Some of these newer and better models are quite expensive . Undoubtedly, the prices will come down. Some manufacturers and enthusiastic users claim these units are very accurate.
Prudence argues otherwise.
Before you go into the field, you should plan your project to insure that field work is done as efficiently as possible. Planning should include deciding what features you will be mapping, whether they be points, lines, or areas. There are computer programs available that allow one to calculate how many satellites will available in what configuration over a specified area at a specified time. You then read the data directly from the screen and record it in your field notebook, or you can store it in memory. If you are mapping lines or areas, simply walk, drive, or move along the line or perimeter while the GPS receiver logs positions continuously.