The biggest thing for me on the switch is feeling like a newbie again and not understanding or being able to guess where Neko might go. On Lantus, I could get a +4 at night (before bed) and pretty much know if I had to get up again to test or not and would get some sleep some nights. Now, not so much. So, there is a learning curve again. I really want to be able to get to that point where I can say "it's safe to go to sleep". I'm not there yet, so be prepared to test a bit more for a while.
Neko's Lev cycles are almost timed like Lantus with a two hour lag. However, it's not so much a nice C shaped curve anymore. On Lantus, once Neko was headed up, she kept going up. And Neko still bounces during the day and drops at night. That part of her hasn't changed a bit.
Neko was never bothered by any sting at higher doses of Lantus, so no change there going to Lev for us. And lastly, you start Lev on 70% of your old dose, then have to go back up again. That only took a week for us, might take longer for you - or not.