Open browser, go to the messenger part, log in, as simple as that.
First impressions:
- no ICQ groups - that sucks - I used to use it a lot
- aliases of people are retained ('MG Zas' for example) - which is a backup for groups ('group MG -> user Zas' becomes 'MG Zas').
- Cyrillic characters work fine (if it was working with my other client - Pidgin/Gaim)
Concerning the standalone client - Google Talk - I have no idea if it works there - Google have a pretty wierd update policy - they update silently and only some clients - it sucks.
After all - it's usable