I usually get a better position (as white) from the Marshall - which is not to say I haven't lost, but a basic tempi count shows white will have the edge as long as (s)he doesn't fall asleep at the board......also, in blitz a lot of people will fall for cx Nx e4 Nf6 e5 Ne4?? f3! (trapped)
To me the Marshall looks like a slightly crappier Alekhine's defense.....
... actually quite common amongst amateurs, but rarely seen in higher-level play. The main problem is that, if white chooses 3. cxd4, then he/she can displace the black piece used to recpature with 4. e4. Otherwise, 3. Nc3 is the follow-up by white. What do you think?