Pros

-No paths, specializations, affinities, or other branching choices to make. Assassins are very straight forward.

-Faster levelling than any other race (which makes mob deaths while learning or exploring sting less)

-Ability to see almost anyone in a civilized area without using potions or other preps (in the wilderness you won't see rangers or outlanders though)

-Ability to hide and stay out of site when you chose also almost anywhere with only a small percentage of the population able to see you (great for when you want to stop and read a help file or something.)

-Very resepctable stats

-When you do get into pk you're much more likely to have a favorable range

-Rp'ing a human is usually pretty easy for most people

-No vulnerabilities

-The ability to be neutral or good which keeps half the mud from just randomly wanting to kill you usually. (As opposed to evil where almost all of the mud will want you dead.)

Arial would be a second choice because having permanent flight comes in handy in a lot of situations, but then you have to deal with the vulnerabilities (anyone with access to lightning or water is going to hurt you a lot) and you'll be slightly frailer and weaker.

I also can't stress enough playing a friendly role tends to make life easier for new people. Making friends gets you people who will often help you in lots of ways, ranking, rping, directions to shrines, pointing out good places to go, etc. You can play the sphere anger attempted bad ass as your first character if you like, but don't be surprised when no one wants to talk to you an you don't learn much about the game. You will learn many, many times more by making friends in game.