I have exactly the same problem. Restoring can take and extremely long time OR you can be hung and it is hard to determine which is which. Having said that if you are stuck on the initial software install after verify then you are almost certainly hung and have to restart.
The points about try and upgrade before going for the restore, how to get the device to link to i-Tunes and the hard reset are all important but these things but they neglect a bunch of things that are just always a problem to me.
Apple software is always less reliable when running on windows and non apple hardware (which it always is in my case)
a) unplug any USB device you don't actually need to run the restore
b) Don't use any extension cable, cheap interface cable or one that may be damaged (chair rolled over it, badly creased/folded)
c) if you have USB 3.0 and USB 2.0 ports use the 2.0 ports because on the iPad 2 (and even my iPhone 6) it seems to struggle (ie hangs) on high speed
d) to do an upgrade always plug in your device and do a backup (noting the points above)
e) don't back up to iCloud for restore purposes as even if your iCloud storage is large enough for your entire device you will be limited to the download speed of your internet link (not to mention if your internet link goes down you are stuck until it comes back up)
f) Before any upgrade make sure you have plenty of free space (2 Gigs?) assuming you are updating on the device not using iTunes. Delete stuff if you need to ensure there is plenty of room. You have to have room for the update and enough space for an additional 1.3Gig or so beside as whilst the update may be only 180Meg it seems to build the entire iOS version in storage, which is more like 1.3 or 1.4 gig and then verify it before copying over your current version. This makes sense and is a good idea just make sure you allow enough room for it. Doing the update from iTunes takes less storage but not a massive amount less necessarily.
g) NEVER EVER EVER try and update using iTunes and a windows PC. Back up to the PC (not iCloud) and then upgrade using WiFi download to the device and upgrade under settings
If you don't have any USB 2.0 ports you can try using a USB hub that is only 2.0 but that does depend on the quality of the hub, some cheap ones will do a disconnect that will completely ruin and restore forcing you to restart it.
Yes USB 2 is slower than 3 but not in the case where the high speed seems to crash the communication link almost every time sooner or later.
My 4 cents worth
I do really wish Apple would improve their windows software and work on the reliability/ recoverability (read error detection and correction).