I have been using this for over a year now, mainly on my Allez sport 18 so that presta value, but i have on a large number of time used the other for my everyday bike or to help a friend out,
Yes it cheap, yes it light, but the holder fits onto the bike under one of my bottle holds and the pump is never in the way, it come with plastic screws to put it into place, but just us the ones with your bottle hold or are on the bike, anyone that uses plastic screw are dopes as they will break! and block the screw hole!
Changing the Value set is easy if not fast, takes about a min but it not done that much so its fine, you remove the screw on ring were the value goes in, pull out the rubber i use a key to start it and than there another bit of plastic which you remove and put back in the other way around you than put the rubber in the other way around too, and but the cover back on. Same as most pumps it size.
It get you up to about 60 psi which is half of what my tires need but if your get a puncture, it will get you up and run again and all the way home. 60 psi is what most bike going in and out of the cycle would be happy to ride at. (well most people i see in Dublin city are on two flat tires :( )
Having used it for a year i would buy it again if this one broke, but i am looking at getting a pump that get up to 8 bar thats around 110 psi for my racer as i am doing a lot of long distance touring, but i will be keeping it and put it on my everyday bike which at max get 50 km in one trip which i don't mind cycling at 60 psi. but when your 200 km from home and have another 200 to go it be nice to have the full 8 bars but if your not tour you don't need it.
Note this is NOT a pump you should be using to pump your tires up all the time, it for when your out and about and get a puncture, your everyday pump should be a large foot or two handed standing pump WITH a gauge on it! This does what it was build for and it does it very well!