Pros: Has the most solid fundamentals of any major MMO. Broad diversity of classes that each manage to perform in a distinct manner, while at the same time allowing each to fit into 1 of 4 'major roles' that every party needs (Tank, healer, dps, scout). Tradeskilling is actually useful, which is a rare feat. Consistent content updates and quality tuning. Game is tremendously solo-friendly. Tertiary link to a fun CCG. Game has truly improved with age.
Cons: The WNBA also has extremely solid fundamentals, and is about as popular as EQ2. Scenery is beautiful, while PCs and NPCs have a distinct 'Poser 2.0' appearance to them. Population consists primarily of housewives and the children of housewives, leading to a distinct impression you're exploring a fantasy world located inside of a suburban K-mart. Soloing too much makes you feel like a creep. Native UI stinks, though it can be replaced.
Overall: Hey, they're letting you play the game for free until the end of September, so go for it. They're trying like crazy to get people to play, and it shows.