Mistakes, plenty to go around. The good decisions would be a bit more interesting
Mistakes
---------------------------
Sony
1) Not enough launch units, but didn't fess up until late in the US launch - Hurt publisher goodwill as they suffered financially and really recognized how dependant on Sony they were
2) Poor developer tools - This really hurt developer goodwill
3) Not recognizing the importance of online
4) Indecision regarding HDD and online apps (Real Networks, AOL, Cisco, etc)
Nintendo
1) Not reacting to the shift in demographics of this industry
2) Not procuring enough third party content (even if it's multiplatform)
3) Absolute dismissal of online.
4) Concentration on GBA/GCN connectivity was weak.
Microsoft
1) Extremely poor Japanese relationships and support
2) Not enough exclusive third party content, leaving Sony with the Lions share
3) Inability to sign EA to Xbox Live early on
4) Launch in Europe was much too late in the game