After few days of troubleshooting there was just issue with permissions for ECE folder. I can't say if there was bad settings before ES7 but just add Read&Write permissions for "Everyone" solve our issue.
In process of TS we see some great stuff like
it's possible that there is need or be better to have opened port 9001 (documented just for v12) but this was just request from TAC, not active connections :)
issue was logged to win events in applications logs as
"The HTTP Filter DLL C:\ECE\eService\installation\egain-plugin\isapi_redirect.dll failed to load. The data is the error."
"Could not load all ISAPI filters for site 'DEFAULT WEB SITE'. Therefore site startup aborted."
Because issue was simple, troubleshooting was really hard :)
