I was like completely OBSESSED with PW when I first started, and I played non-stop for five months. Ended up on lvl 73, winged elf!
But after a while, I got bored, cause it took so long for me to lvl and I felt like I had experienced a lot of PW already so it just got boring.
Good game, though - very good game, especially since it's free.
I also find it boring especially if you manage to have a character with a high level. I've even created other types of character but I ended up quitting the game for awhile. Anyway, I find the best way to level your character is to do quest rather than hunting for monsters.