Already, no problem installation, setup is easy, we download, hop it's done, the instruments provided are convincing and impressive library provided. No incompatibilities especially with virtual instruments I use regularly, except that it took the Upgrader ... but that's normal. I almost have not used the manual to get into it ... but my experience with Logic 8 probably helped. I use it in a home studio setup (so no live)

SUITABILITY/PERFORMANCE

When recently I decided to change the material of the studio I opted for an Imac / SSd 256GB / 5i processor with an external HDD for backups and Logic works perfectly with this config. Question stability no problem unless you do a little risky stuff but otherwise no real worries when the CPU load ... I do not even think.
I was a little scared saw everything we see on the forums about Yosemite but I have had no problems with this new version of Apple's OS.

OVERALL OPINION

That's one month that I use, and working every day with, I begin to get an idea about it. Do not talk about the price that is the lowest in the market and of course I would do this choice eyes closed.
This choice was guided by the confidence I have in Lengeling Gerhard and Chris Adam programmers who are responsible and that I enjoyed working with Notator I then passed Logic 8 and now (I do not know if are always the ones who make development) Logic X.
Logic X developments for what I've tested to date are well regarded: the tracks of automations that are right next to the automated track, zoom the keyboard they were "sting" in Digital Performer which is really handy, and if we add to this a look that is very successful I can say that I am satisfied.
In practice I find that I never do the mastering of my pieces with Logic but with Digital Performer which I find most useful tools in particular regarding audio editing but now, they are only working habits, we can not be good at everything and Logic is really perfect for composition.
Maybe there-he has things to improve so I put only "excellent"!