It will depend on what is offered as to whether traffic will come. As for income from ads, the likely downloaders will avoid those like the plague since they are there for a different reason and probably know the difference.

Several years back it was very popular but I think the market has being going down slowly. The popularity of sites such as download.com, tucows, filehippo, etc, has being going down significantly over the years, at least with regards to desktop software (attributed to the rise of mobile apps, app stores, etc).

In addition, more internet users are getting savvy and using popup blockers, which will decrease the revenue from ads significantly. In my opinion, it is not a very lucrative market anymore. However, there's no harm in giving it a try.