It is the only site I have been to during my time in the sport. I started off renting guns from them, very nice about it all. good customer service and they seem to know what the're talking about.
They do two types of days Pro-am and Bootcamp:
Bootcamp is based towards newer players, they start by day playing a game with all the new players. They take you to the Village section (at least they did with me) and give you an in-depth overview of Airsoft and how to play safely as well as teaching you about the honor system.
There are still a lot a regulars that show up on Bootcamp, I try to help them out whenever I can.
They also hold a raffle on some Bootcamp days( not too sure, correct if wrong) 1st prize is a pistol, 2nd is some form of optic and 3rd prize is some consumables such as BB's and grenades.
Pro-am for the more advanced player:
Don't have the pre-game newbie game get through safety briefing and then onto the first game. Always played on Hill 60 (the bunker by the starting area) after that they have a number of different games played in the CQB area and across different areas of the playing field. CTF, defend the base and some special games they make on the day.
The field is HUGE and they do provide maps on the area the are okay (not the best) but you get used to the field after a time (still don't know all the names of areas myself)
TLDR: Great field, friendly to new player and also suited for advanced players. IMOP, best Skirmish site in Essex