I really don't think it's that difficult. Obviously the "good" games are decidedly in the minority of everything that comes out, but I really don't think it's more true of the Wii than it was of the NES or PS2.
Most crap games, I can tell they're crap just by looking at them. Obviously a game called "Paws and Claws Pet Vet" (a random example I just took off the upcoming Wii games list) is going to be a piece of crap shovelware game that I can safely ignore. The fact that it exists doesn't in any way hinder my Wii purchasing, or make me less excited for, say, Muramasa.
It is true, however, that the Wii has much worse graphics, so people who place big importance on that (remember when "graphics whore" was a common insult?) will never get much out of the system. And it's true that it doesn't have all the same types of games that the 360/PS3 have, so if you have rather specific tastes and only like Tom Clancy games and Bioware RPGs, it's not gonna work for you. But people who say it has nothing worthwhile (or almost nothing, or nothing coming out) are just on crack. I'm not even a huge fan of Nintendo, I've never cared for Smash Bros. or Mario Kart, and I don't like any of the "Wii ___" games except Wii Sports, and there's still been more Wii games that interest me than I can keep up with. I own 60 Wii games and still have a sizeable want list.
Can you give some examples? Most Wii games I play control fine. There have been some disappointments (Samba de Amigo immediately comes to mind), but in general I don't find myself fighting with the controls. I think The Conduit controls better than any dual analog FPS.