It certainly makes it easier if you're on your own. I use this http://www.ebay.co.uk/itm/Hand-Held...406?pt=LH_DefaultDomain_3&hash=item3f35701886
Personally I don't get on with them, the seal to the nipple is not good and allows air to be sucked in ie you can't tell if there is air still in the lines. The tubes need to be able to hold a vacuum so are inherently stiff and inflexible. It could be the set I got was a cheapo off ebay, it certainly isn't premium like the Mityvac etc. My setup is now speed bleeder nipples and a soft silicon tube attached to a large syringe.
Useful if you are pulling through fluid on new lines/repaired calipers, if it's a normal refresh fluid I still use the old fashioned way Got a Mityvac and IMO you need to PTFE tape the bleed nipple threads and tie wrap the hoses to the Mityvac to stop it pulling air in
I've got a Mityvac and normally revert to using the old method of pumping the master cylinder and opening the bleed nipple. The Mityvac's just really fiddly. The pipe won't seal on the bleed nipple unless everything's just at the right angle. You're never sure if you're pulling air from the lines or if the bleed pipe just hasn't sealed. Then you'll put the mityvac down and the end will come off the bleed nipple and, due to the rigidity of the pipe, it will flick brake fluid onto the bike
Then there was the time that I attached the pump to the wrong side of the collection pot and duly sucked up a tonne of brake fluid into the pump itself. That was a bit messy
cant see a need for one on a bike tbh.it's easy enough to reach all the calipers and pump the brake lever at the same time,opening/closing the bleed nipple.but maybe I'm just old skool (not so old though that I know that's how the kids spell it )