Unfortunately there is far too much drama-queening with user revues.
The two main issues were:
The attempt to replace mDNSResponder with the new, ground-up re-written discoveryd, which was a total....ermm omnishambles. In 10.10.4 they reverted to mDNSResponder which has stabilised things
The new Photos app which, besides having the stupidest app name ever (try googling for help on it), had a lot of issues and loss of functionality (caused, again, by a ground-up re-write).
There is quite a bit of divided opinion about the revised iTunes with iTunes Radio - it definitely needs tiding up and its relationship with iTunes Match property spelled out.
If you are concerned then wait for 10.9, which is billed as a Snow Leopard-style optimisation release. If you're happy with 10.8 and it does all you need then there is no rush.
Edited by ian_c (Mon 31-Aug-15 13:55:22)