Q. Is it recommended for a woman to count Sefirat Haomer?

A. Mishna Berura (489: 3) quoting Magen Avraham writes that although women are exempt from the mitzvah of Sefirat Haomer as it is time sensitive, they have already accepted it as an obligation. However, Mishna Berura presumes that in his own districts and settlements, tradition has it that women do not count Sefirah at all. He also quotes Shulchan Shleimo that the ones that do count, do not recite a blessing, since it is likely that they will forget one day to count (since they do not regularly daven Maariv) and some may also not understand the meaning of the count.
Those who follow the Sephardic tradition maintain in general that women do not recite a brocho on mitzvos they are exempt of doing. (Rambam – Temidim 7: 22, Shulchan Aruch O.H. 587: 6) Not only would the brocho be in vain, also in the particular case of the counting of the Omer, they are enjoined not to count at all, following the Zohar (Raya Mehemna – Emor p. 97) that the days of Sefirah are not auspicious for them. (Yabia Omer 2: 30: 4, Yalkut Yosef – Sefiras Haomer p. 416, Chagim Uzmanim p. 259.)
However women who follow Ashkenazi traditions do recite brochos on mitzvos they are exempt (Rabenu Tam, Remah – Shulchan Aruch O.H. 587: 6.) Although, Pri Megadim maintains that this applies only to mitzvos were an action is involved as Lulav and Shofar and not verbal mitzvos like Sefira, many Poskim disagree. It should also be noted that Ramban’s (Kidushin 34) position is that Sefirat Haomer is not a time sensitive mitzvah since it is part and parcel of the Yom Tov of Shavuos or depends on Pesach. (See next question)
Horav Shlomo Miller’s Shlit”a opinion is that women who desire to comply with this mitzvah and are steadfast in its constancy, can do so and with a brocho. (See similar opinions quoted from Horav Eliashuv zt’l in Hilchos Chag Bechag and Horav Ch. Kanievsky Shlit”a in Dole Umashke and Piskey Shemuos p. 16)

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a.