The new "H" models of eTrex have a lot going- memory card, road route calculation, but most important is higher sensitivity. My old Vista would lose signal all the time under trees, while my new Vista HCx holds on to a signal tight even in my pocket while under trees. I bring it jogging all the time, and even in a fanny pack it never has a skip in the track log.

EDIT: By the way, they do have labels on the buttons- there's a cryptic icon molded into the rubber button. Good luck figuring out what they mean though!