Offshore work can be fun, but it can also be very boring. I think you spend around 80% of your time waiting around and the other 20% working your balls off. The pay though is good, as are the other benefits. If you work in the UK sector, forget about any tax breaks. Gordon will still get his paws on your cash.
Be aware though that working offshore has some serious downsides, you will spend a lot of time away from home, you will also miss importnat things like birthdays, Christmas and so on. This can be tough on relationships.
Working offshore is VERY safe. Safety first is drilled in to you. Idiots that endanger others are not tolerated. The most dangerous thing you will encoutetr offshore is the food, depending on the rig, you can expect to put on quite a few kilos.