My only complaint with Union is that my Union SL's have the smoothest ankle strap release ever, but the toe strap is the biggest bitch. If they were both difficult to release it'd be more tolerable but to have one slide out easily and have the other one be so finicky just emphasizes the issue...
If you're not already doing this, the easiest way to release it is to push down on the back end with your thumb while pulling up on the front with your index finger.
It is easier by doing that, but still kind of difficult to release. Union has actually added a release lever to the toe ratchets on most of next season's bindings.
The higher-end ones will still not have one, but they will have a new release mechanism to make it easier.
Hope that helps.