The main reason to subscribe: it's really, really fun. Aces High 2 is in development, so you'll get a chance to get in on the ground floor there. You'll learn a lot about WWII airplanes, weapons, and tactics, and about flying in general. You get two weeks of free trial, so go for it and judge for yourself.
Verbal abuse: It happens, as will happen anywhere with large groups of people. However, generally the AH community is a bit older than the everquest/quake crowd, and as a result, more mature. You can easily squelch anyone you deem offensive. Moderators boot or squelch people that are way over the line. And if you see anything really bad, you can take a screenshot and email it to HTC. They personally take care of some stuff. I've never gotten into a real argument in AH. Generally, if you don't go looking to argue, you won't find arguments.
Kill stealing: Happens, but not enough to make me care. There are probably 10 kill-steal whines for every actual case. Most of the time, it's just that someone else was shooting at the same target and did more damage. Nothing underhanded at all.
Runwaying: if you mean vulching (shooting planes taking off), yes it happens. Perfectly legit tactic. Main way for Allies to kill Me262s in WWII was to get them taking off and landing. You want to fly to the fights here, not take off in the middle of them. Basically, if a field is vulched, don't take off there.
The people are generally very nice and helpful. Ask for help, and someone will almost always offer you a hand. The bulletin boards are a great source of info... you can search for others who have asked your question, or ask it and recieve multiple answers, from multiple viewpoints. Players make great websites dealing with training: netaces.org is my favorite. Go there for tips on getting started.
There are almost always at least 200 players in the Main Arena (at least whenever I look). At primetime (USA nights), you'll see 400 to 500 on.
Hope this helps. Any more questions, just ask.
