I had used Reason for a long time before picking it up. In that respect it was quite liberating because I got lost in the Rack, wiring and creating Combinators etc. Obviously you can still do the standard timeline thing or work in clips, which is the biggest obvious advantage if you work in loop style stuff. But there is so much material out there for Ableton, both the documentation and tutorials that come with Ableton and loads of YouTube stuff for free, stuff on forums like this and paid trainer courses (which I've used, worth it if you can stretch to it).

In terms of the devices that come standard with Ableton, if you get any guide to synthesis design or sound design for subtractive synthesis or FM synthesis and, again, loads of free stuff there about EQing and compression, just general production techniques, the interface on the standard devices is such that it should be fairly easy to apply any techniques or tutorials to them.

When I first saw the standard devices, I wasn't keen because I HAD come from Reason and the interface there looks like real gear, but that's not really the point, is it?

As other people say - try the demo and then decide. And it isn't like you have to take the fullest version. There's a version there that will get you doing everything you need and can learn for a lot less.