Martin's current crop of less expensive guitars, basically anything below the "Standard Series" (18, 28, 35 etc.), are built using Martin's take on a bolt-on neck. They call it a "mortise/tenon" joint but it's a bolt-on in thin disguise.

One minor disadvantage of a bolt-on neck is that it's possible to strike the bolt when drilling a hole in the guitar's heel to install a strap pin. It won't hurt the bolt, but you'll probabaly have to drill another hole in order do get the strap pin screw to bite properly, and you'll have to patch the mis-drilled hole. If you don't know exactly where the bolt is, it's probably best to have a luthier do the job, simple as it is.