Depends upon which flavor you find objectionable. If you don't like the taste of very strong green tea, then yerba mate may not be for you. However there are several other factors that can lead to yerba mate tasting bad. First is the quality and freshness of the yerba. It should be 6 months or less since it was packaged (check date stamps). It should be made with 80-85* C water (too hot, and it will be super bitter). Whether the yerba has stems (palitos) or not (despalada) can make a difference, stems contribute a bitter taste to the drink. As has been mentioned, knowing how to load the mate and get it primed can also have an effect (ideally, you're going for a slightly nutty, green tea flavor, with a tiny bit of sweetness). It also needs to be a high quality brand, which can be very difficult to obtain outside of S.America. Some high quality brands are:

- Taragui (Argentina) - La Merced (Argentina) - Union (Argentina) - Canarias (Uruguay) - Sara (Uruguay)

For preparing mate cold (called tereré) - La Rubia (Paraguay) - Pajarito (Paraguay)

... and though highly controversial, you can add sweetner to it to make it less bitter, at least until you palette adapts. But be prepared to be chided with "si no es amargo, no es mate" if mate connoisseurs catch you doing this.