Surfers who hate the restriction on their arms from traditional wetsuits often choose the long john. This wetsuit still gives you the warmth you need and great paddling flexibility. This type of wetsuit is sleeveless – there is no restriction placed on your arms at all and is ideal for paddling. To keep you warm, however, the long john wetsuit has full length legs and thicker neoprene on the body area.
This particular type of wetsuit is most often used when the water is in the 64 and 68F (18-20C) area. The seams are typically blind stitched and glued so they will be almost completely waterproof which will help keep you warm while in the water. But because this wetsuit has more and bigger openings there will be more flushing than with a regular wetsuit with sleeves.
There is also a short john version with short legs for even warmer water.
If you want to learn more about which wetsuit goes with which water temperature and what are the factors that influence the feeling of cold check this article.