I have just try new Opera 18 in Windows 8 and unistall it after 20 minutes later.

These are the reasons or missing features:

1. Sessions: there is no sesions any more. I only use opera for all my Business Web Sites. I have about 6 sessions or Business Groups. But in V. 18 I can't find sessions features anymore.
2. I import all old business sessions into V. 18. it will successfuly open the default session in the first time which has 3 Opera Windows for each Business Topic. Anyway, after closing all windows and re-open it again, it will show only the Last Windows when I existed. (Default current Openning Windows setting)
3. With setting on the 3rd options in the setting (select current openning pages). If I choose this setting and exit the Opera, the new opening windows will have ONLY 1 Windows not 3 as the original Sessions. All > 30 Urls are openning in the same windows. Imagine what it looks likea and how it's so difficult to work with.

Recommendation:
Please add Sessions Features into all of your New Versions. This is the best of Opera and make it OVER The Top.

Now, Operat is still my Business Browser and, of course, Back to V. 12 for Sessions Features.

Thanks & Bet Regarsd