HTML5 has a lot of hype going for it recently. Unfortunately, the facts do not support the hype – HTML5 has:
- Major unresolved security issues
- Mobile browser support which is very inconsistent across devices and carriers
- Desktop browser support which is inconsistent
HTML5 does not currently deliver the ever-elusive “write once, deploy everywhere”. Based on HTML experiences (which is a simpler and less featured spec compared to HTML5) that dream is unlikely to be realized.