It seems to be effective in stopping bots.
In terms of naming fields, it depends on the bots themselves.
- Some will fill in any field.
- Some will fill in fields that look like that should be submitted (like "address").
So, we now recommend that you name one field with a sensible name (such as "address1" or "addr", or "your_name") and one field with a nonsensical (and random) name (such as "f2epab5").
Make sure the sensible name isn't a name you're going to use for real data! The "sensible name" field should be empty (so bots are more likely to fill it in) and the "nonsensical field" should have a random value.
To be extra sure, why not add one or two more additional fields, and place your sensible name fields near your real fields on the form.
Remember: the aim is to trick bots into revealing themselves. So, you have to think how smart bots might operate as well as dumb ones.
The other thing is to use different methods for hiding the Reverse Captcha fields.
Some examples, using CSS:
<input type="text" name="addr" />
<input style="display:none" type="text" name="addr" />
<input style="visibility:hidden" type="text" name="addr" />
<input style="position:fixed; left:-10000px; top:-10000px;" type="text" name="addr" />