France has weathered the global credit crunch well compared to many other countries. Prices in Nice are significantly lower than the surrounding areas; with good reason however. Nice is not a particularly nice city and unless you purchase in the right area, you will find it very hard to rent your property, long or short-term.
More than any other city that I've lived or invested in, the "right area" is judged on a street level rather than a 'quartier' level. Routinely in Logic-immo (real estate publication), you can spot 1 bedroom apartments on the Promenade for E120k, 3 bedroom lofts in Vieux Nice for E200k and large villas in the Nice hills for E300k but likely, they'll be on the Californie end of the Prom, buried deep in some obscure Ruelle and without access respectively (none of which is appealing to tenants or other investors) so you *must* have access to local knowledge if considering a purchase in Nice or you will get burned.
That said, because prices are lower than most other places in PACA, the yields are reasonable. You should easily be able to get 6/7% by doing holiday rentals in the summer season which will also give you a few weeks to use the property yourself. If you can get that yield in a good location; Promenade (east end), Vieux Nice (anywhere within 5 mins of the Palais de Justice), Port (on the port only, nearby is useless), Rue Giofreddo (the Jean Medecin end), Carre d'Or + Rue de la France, you'll be onto a winner. Personally I wouldn't recommend going outside of the area formed by Blvd Gambetta, Blvd Dubouchage and Place Garibaldi. Properties outside that area don't rent well.