just installed Kububtu 15 with plasma. yikes, there's no task bar or "start"-like menu anymore. How do I get back those interface features I'm comfortable with?
You may need to add a few widgets to do this, I think you can right-click to bring up the appropriate menu. It was a bit of a nuisance but in about 10 minutes or so I was able to get a reasonably good start menu and taskbar. It was disappointing that it didn't import the profile and layout from v4, though.
I could probably look up exactly how it was done, but right now I've switched to XFCE for the time being, because Plasma 5 crashes if you look at it funny. This on an nVidia card with the proprietary drivers so I think there's more to this than a bug in the Intel driver.
One important thing to note is that Plasma 5 drops support for the little systray icons, apparently they were powered by the XEmbed system which is considered deprecated. This means things like Dropbox and WINE applications which use the systray won't appear. There are workarounds for this (alternate libraries that implement a systray) and in the case of Dropbox it looks like they've recently added support for whatever new library or protocol replaces it.