Every system I have ever owned has had its strengths and weaknesses ...
Right now I would say that the Wii's biggest weakness is third party developers that have their heads up their rear ends. From the begining (Tokyo Game Show 2005) it was clear that Nintendo was producing a system which was going to be far more successful than any system they had made in recent history; by the time E3 2006 rolled around and the line to try the Wii was 6 hours in comparison to a 10 minute line for any PS3 or XBox 360 game these developers should have realized that they needed to produce something for the Wii. Now many developers are years behind where they should be, and they see Nintendo's success without understanding why Nintendo has been successful; certainly, Nintendo's 'Blu-Ocean' games have done well for themself but it is Nintendo's conventional ("Core") games that they have been producing for over a decade that have really shined.
Developers HAVE TO stop seeing Super Mario Galaxy, Super Smash Bros. Melee, Mario Party 8, Mario Kart Wii, The Legend of Zelda: Twilight Princess, Super Paper Mario, Mario Strikers Charged, Resident Evil 4: Wii Edition, Metroid Prime 3: Corruption, Sonic and the Secret Rings, Lego Star Wars: The Complete Saga, Resident Evil: Umbrella Chronicles, MySims, and Red Steel as "The Exception" ... These games in content and gameplay style would not be much different from what they're producing for the XBox 360 or PS3 but do create intuitive controlls using the Wiimote and have a decent ammount of effort put towards their visuals.
Certainly Wii Sports, Wii Play, Mario and Sonic at the Olympic games, Wii Fit, Big Brain Academy: Wii Degree, Carnival Games, Wario Ware: Smooth Moves, Rayman Raving Rabbids, and Rayman Raving Rabbids 2 have been very successful but constantly trying to clone the success of other games in a market you don't understand will only end up with you struggingly to define yourself.
At the same time, don't think that my XBox 360 is off the hook ...
Most of the games I have played for the XBox 360 seem to be designed with a "Bigger is Better" mentality and I am often left scratching my head and thinking of the scene in Big where Tom Hanks asks "I don't get it, what is fun about that?"
