When version X, that is the number 10 and not the letter “X”, first came out, was not sure what to do. Decided to take a chance around 10.0.6 or so, never really looked back since then.
Despite some of the “It looks like iMovie” or “It is a toy” comments floating around, the current version is very much pro grade software.
A few things to keep in mind is that there is slightly less integration between FCP X and Motion 5 as there is with the “Dynamic Link” with Adobe products. In previous versions of FCP there was “Send To Motion”, not so with X, something to consider. On the flip side of the coin, you can create custom built generators, titles, effects, and transitions inside of Motion to use in FCP X, which can save time.
Two things that I like about X is the magnetic timeline, which may take a little effort to get used to, and the organizing features. Connected clips will allow you to make around big chunks of clips, keeping everything in synch and avoid clip collisions. Finder tags can be brought in as keywords to help further organize.
Media management has improved as well, this was implemented a couple of versions back.
You might need X to 7 and 7 to X if you have another editing software in the mix. Both are available in the App Store, but then again, you might not need them.
The only downside is no keyframing of color correction, and keyframing needs some improvement.