i was glad to do the upgrade. From 7 to 7.5 was not that expensive and you get a lot of new stuff.
Groove agent 4 is awesome by the way. And actually this seems to be a very stable upgrade. Working several weeks now with it and no crashes, not one error, no issues at all... On the forum there seem to be enough people who share this view. But a big difference with the release of version 7 initially.
Another thing to notice: you're old installation remains so the old songs will boot up with the previous release so nothing gets impacted if you don't want to.
Cubase 7.5.x, vienna ensemble pro 5,
Master:laptop Clevo, W170, i7 2760Qm, 16 gig, 2xSSD samsung 840pro/evo, +touch screen
Slave: desktop: Titanus, Q8440, 8 gig, 2x WD HDD + SSD
Sound: Motu Ultralite MKIII (usb)
control: Synergy, novation zero SL
vsti: Steinberg, East West, Vienna, Native Instruments, and a lot of others