The site is not very big, but is well worth a visit if you have an interest in Troy. The site is a bit of a jumble, as Heinrich Schleimann's excavation was hodgepodge, so it's worth it to get a map. The Trojan horse is pretty kitschy, but a fun photo op.
For WWI buffs, it's worth it to stay in Canukkale to combine a visit to Gallipoli as well.