web2py is better because it is faster, it is easier to use, and is more stable than other frameworks. It is also always backward compatible.
You should read the detailed comparison of features here:
http://mdp.cti.depaul.edu/examples/static/web2py_vs_others.pdf (if you find something is incorrect let us know and we will fix it)
or the wikipedia comparison (less detailed)
Finally you may want to read benchmark results for the web2p ORM vs other ORMs popular with other frameworks
If you feel the need to say something negative about this framework without having tried web2py and without going to substantiate it with hard facts, please take your rant somewhere else. web2py respects other frameworks and other developers. We have learned a lot from Django, PHP, Pylons, Turbogears, web.py, Rails, etc and we do acknowledge that. So, please, respect us.
If you know Django you may want to read this
If you know TurboGears you may want to read this
If you know Rails you may want to read this
If you know PHP you may want to read this
This is the web2py FAQ, not a blog.