It depends on the objective. If you're looking for a place to "park" your excess funds, it could be a worthwhile component of an overall strategy. But for the individual looking to begin accumulating capital, there are other means that will produce a more desirable result.
While nice homes in desirable areas rent quickly (I have two that never stay vacant more than a few days), as an overall investment strategy such properties rarely yield a decent ROI if purchased today. This is largely a residual effect of the market collapse a few years back. Lenders now require a minimum of 20% down and a six-month cash reserve for each additional property owned, including one's own residence. Tax write-offs notwithstanding, it can take years to break even.
I personally investigated the possibility of purchasing additional rental homes, but decided against it. For my situation, I think I made the right call.