Bundles can last for a month or more, with o new bundles on the horizon. Even then bundles seem to mainly be seasonal with a few thrown in between. This means it may not be the best choice for those looking to get new games daily or weekly.
Many times, developers have provided Groupees with keys and then not been paid at all. Several times, they have not been paid in full. Any unused keys that were provided to Groupees are not returned to the developers (while most other sites return unused keys).