It can do the slowdown, you can load backing tracks, it has a built in tuner (better than my $40 fender one) tons of amps and effects models.
It's also a GREAT 4 track recorder.
Blonde Thinskin '59 Jazzmaster, '52 RI Tele, '66 Harmony Rocket
Silver Face Deluxe Reverb
SunFace w/ Sundial - ProCo RAT - Fulltone GT-500
Keeley AD-9 - Boss CH-1