Window management has tons of options and actually usable virtual desktops - there is even a concept called activities where you can further configure your work spaces. Terminal emulation should be fine. Konsole is mature. There is also a Quake terminal for KDE called Yakuake. Gnome Terminal and Guake work fine through.
Biggest frustrations (not really frustrations as I could solve the issues after spending some time with the configuration options):
- The Desktop in a widget - you can easily configure it to a normal Desktop but the widget stuff is not really that great IMHO.
- I really did not like the default look. I've switched to QtCurve now and I'm quite happy. Some Desktop effects where too much for me but it's easily configurable. If you are familiar with KDE 3.5 you'll feel at home.
- I disabled the semantic Desktop. It hogs quite a few resources
- KMail is not really usable. But I didn't tried too hard. Thunderbird runs fine
- I'm using Pidgin because Kopete and Empathy do not support OTR encryption as far as I know
Overall everything is configurable. Which is really confusing at first. There is a learning curve but IMHO it's worth to take the time. 4.11 is really stable for me. No memory leaks or other strange behavior - quite low memory footprint. I'm really impressed. Sorry if I sound like a shill here but after using Unity for the last few years it was worth making the switch. YMMV