I have to use it daily in accompiament to Perl and my comments back are:

1. Platform dependant (unless you pay massive amounts)
2. Hard to separate template and program
3. Templating almost exclusively SSI
4. The OO functionality does not allow for inheritence (under VBScript at least)
5. Usually there isn't TMTOWTDI unless you buy a dll library
6. ASP lacks syntactic sugar
7. Its too easy to write a bad script and not know it. Its easy to do the same in Perl but you know you have
8. Accessing a database requires a DSN. Theres no DBI equivalent.
9. Oh.. ADO...well ok. But after using it for nearly a year you notice its only really designed for doing things the Microsoft way....not your way.
10. It runs on a server that is too easy to hack
11. You rely on a corporation to bugfix the language which can take anything upto a year (or more). Can you say that for Perl?
12. Can you do more than dynamic pages in ASP? Would you want to?

I have more but I don't want to think about ASP when I'm not getting paid to do so :)