It's not that bad, but can be frustrating at times. Mal'Ganis (I'm told) is less pvpish than most pvp servers. Quests are set to take you into contested territory beginning at level 20. This is Ashenvale and Hillsbrad, initially. Ashenvale is not too bad, but Hillsbrad can be a real bear. STV is also challenging. After that, things calm down a lot until you get to 50+. Both sides like to camp at instance entrances and gank you as you try to enter.
Overall, I like pvp servers. The whol premise of WOW is two factions at war; that can only be experienced on a pvp server. You will always have an occasional lvl?? running around ganking, but there is also lots of support. Usually, if you ask for help, there are some around who will come rescue you. Expect a little frustration from it and slightly slower leveling because of it.
What is really fun is when these types of things turn into a full fledge battle. Shuranda and I called in some guild help in Hillsbrad one time, then the alliance called in reinforcements. So we called in more help. Before long it was a full blown battle with about 20-30 on each side figthing on the edges of Southshore. That sort of thing happens some, but is not all that common. They also organize raids into the capitols. Once, there were close to 100 horde at IF.
Bottom line, you have to look over your shoulder a bit and move a little more cautiously. But all in all its not too bad. There a lot of times when the two faction meet, wave, and go on there way. I would absolutely love to see some of us with Horde toons on Mal'Ganis. I enjoy Teneras and playing the alliance, but my heart still belongs to the horde. It would be great to see enough players start toons on Mal'Ganis so we could have our own guild there too. The Forgiven Too, or something.
If you decide to play on Mal'Ganis, add the following to your Friends list:
Skinless (my rogue)
Necrose (my priest)
Shezap (Shuranda's mage)
Shehan (Shuranda's hunter)
Hosea (Harrison's rogue)
For the Horde!!!!!