Yeah, Derv's start out a bit slow. However, they rock later on, especially against large groups of mobs. Ironically, the more enemies you fight, the more powerful they become.
Despite you having picked up the game already, I should have weighed in sooner. Prophecies has more 'free' skills (in that you do a quest and get them, rather than having to buy them).
Been playing the game for some years now. Very much worthwhile.
Eh, buying the skills isn't that much of a hassle really since i have plenty of skill points and plenty of ingame money (something around the order of 13k)
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I am the nocturnal echo-locating flying mammal man.
I've got over 300k. Actually, there are very few nice farms for it (ANet is often called ANerf for a reason), but you can pick money up at a reasonable rate.