I have the Vortex Solo 8x25 monocular. Used it quite a bit for a couple seasons when bow hunting or stalking with my Marlin 336. Still keep it around as a backup.
It really boils down to your needs. If you want better field-of-view and slightly better clarity, then binoculars are the way to go. If you want convenience, the monocular is great.
I liked that the monocular was lightweight and got out of the way but was there when I needed it. I wasn't trying to identify targets at 100's of yards, I was stalking thick brush and small fields, bow in hand at all times. I found it easier than dealing with a pair of binos in these situations.
I would say I found the monocular slightly easier to hold steady than a pair of binos, particularly if you factor in holding with one hand. I can rarely get a decent view with binos when trying to hold them one-handed, I almost always have to steady against something or use my off-hand.
For my monocular, I got a gear retractor, a sturdy clip on gizmo with a retractable wire built-in to it (maxpedition has these); I then attached this to one of my backpack straps and the cable to the monocular. The monocular was out of the way off to one side of my chest; I could then reach up, grab it, pull to extract the cable, take a quick look, retract the cable to go back to where it was. It had a quick disconnect also for times where I didn't want the backpack with me.
(FYI, the case Vortex provides, at least for the 8x25, is nice and has a snap-on belt clip, BUT it uses velcro to secure the flap that holds the monocular in the case -- it's very loud when opening, so I don't recommend using it for hunting.)