I've upgraded to Ubuntu 16.04 beta 2, and so far, as I've read elsewhere, it's working very nicely.
(One warning: if you have apcupsd installed, turn it off before upgrading! During the upgrade, something happens that causes the UPS battery to look fully discharged, and apcupsd will obligingly shut your system down... in mid-upgrade. Others have seen this when upgrading to 15.10.)
Now I'm reinstalling the various packages I had previously installed, but for FP Complete's Haskell Tool Stack, trying the Ubuntu instructions FP Complete gives (mutatis mutandis for the version) doesn't work, at least as I write. It looks like it's made its way into the Ubuntu repositories, so that sudo apt-get install haskell-stack will do the trick. I'm also quite pleased to see that 16.04 is actually up to date with respect to GHC. ghc --version shows it has 7.10.3. (Now to look to see whether it's up to snuff on the libghc* packages in the repositories...)
