NO escrow service can guarantee total safety. Ie. If the domain is stolen.
Research the seller.
And only then, if pretty confident the seller appears ok, then go ahead and use an escrow service as added protection; additional motivation for them to follow-through in a reasonable time-frame.
Escrow.com holds the funds only, which makes for fast transactions with very low fees.
Sedo.com holds both the domain and funds, which usually adds much time and costs more.
Personally, I prefer using Escrow.com for escrows, but have occasionally used Sedo too.
Escrow services helps ensure the buyer gets what they paid for and the seller gets paid.
To reiterate, escrow does NOT guarantee the suitability / legality of the domain transfer (this is true even with physical real estate; hence the need for property inspection and title insurance) nor the rights of the parties to conduct the transaction. Ie. TM domains, stolen domains, ownership issues, registry restrictions, etc.
Hope this helps.
Ron