Six hours battery life on my old ThinkPad X220, am quite happy with Ubuntu. Also all my Haswell and other Intel CPU machines run cooler compared to my Arch install and therefore heat=power consumed. Colin King, the dev for Canonical does a good job tuning Ubuntu to keep a balance of power and performance. Deadline scheduler keeps my SSDs singing happy tunes compared to default CFQ on other distros.
Give nvidia-prime thats default in Ubuntu a try instead of Bumblebee this time, working good on my ASUS K53C with nvidia 610.
Agreed on Unity. It might be buggy and sluggish in its early versions, but version 7 is simple, elegant, and working. Better yet, with Cairo Dock and a default "Applications menu" you can have a quick access to all the programs just like in Gnome2. Tried KDE and Gnome3 but they just could not deliver the efficiency and easy access to core operations on a desktop.
I like the control that I get with Bumblebee. After finally getting it working, I found it to be better than the Windows Optimus drivers in many ways. I love being able to switch on the Nvidia GPU on an app by app basis. Optimus does that too but the switching is automated without nearly the same level of end user control.
With prime all I do is shut off via nvidia-setting on turn it on, only headache is log out and log in but I only need my nvidia for opencl or CUDA so not a bother, for gamers yes, logging out and in is a pain.
By 12.04 all big headaches were fixed and it ran quite OK, with 14.04 it became mature and rock stable, in 16.04 thankfully not much change and therefore stability continues.
Running Ubuntu 16.04 here after a few weeks of letting it grow through maturation, and I must say it's pretty slick and quick and stable. I like its little brother Linux Mint 18 quite as well. Nice job!