Third party support on the Wii is good (better than GC or N64) the titles that are build from the ground for the console using its motion controls are extremely good. No More Heroes, Madworld , Tiger Woods to name a few.
Im happy that Wii is not receiving tons of downgraded Ports from HD consoles, the ones that appear on the console are pretty bad like Dead Rising.
Some third parties are focused on making games that are very advanced graphically, that are guaranteed monster sales on the HD Twins. And thats where they put their resources and best teams, Wii is left with games that usually fund those "epic" efforts on other consoles, which is sad, because we havent seen a true blockbuster third party game on the Wii.