My unfortunate son dropped an ipad2 off of the top of a bunk bed and the screen didn't survive the sudden change of direction from the metal pole it struck on the way down. It was the typical spider web splintered screen though it still worked (if you didn't mind losing slivers of skin when you used it like running your fingers over a microscopic mandolin).
All in all for my first time ever going inside the case of one of these beasts it went well. I used to take lots of things apart as a kid, but this was a whole different ballgame. The shattered glass made removing the old screen much more difficult than I anticipated, but softening the glue with that heating thing helped a lot.
I ended up breaking both the wifi antenna and the right cellular antenna while trying to get everything out. Partly due to the broken glass making it hard to be subtle removing the old screen, partly because as I got frustrated I was probably using more force than the situation warranted.
However, otherwise the old glass got out and (after a second order to replace the broken antennas) once all of the pieces were back in their proper home, everything worked great. This came as a very great and pleasant surprise to me considering how many things I had to pull out to replace those antennas.
It took longer than I anticipated, probably 5-6 hours between both sessions, but considering this was my first time getting into an ipad I don't think that's too bad. It would be much faster the next time. I learned a lot doing this, had fun with it, and would definitely do it again. Thanks for the awesome guides that made the process so much easier.
Unfortunately I forgot to take pictures, so I apologize for the lack of historical evidence.
Take your time, especially if the screen is broken to start with. I would strongly suggest safety goggles. As I was leveraging up the old screen, the glass was splintering into a kajillion-million tiny shards that were expelled from the glass like tiny trebuchets assaulting my face. You should definitely have some kind of eye protection. Covering the old screen with packing tape helped, but was hard to work around. It was also very hard to get all of the microscopic shards of glass out of the dining room table, so preparing your environment is also important.
One other trick that helped me a lot. Even though it looks at first glance like all of those teensy-weensy screws are the same size, they are not. So as I removed components, instead of dumping the screws into a bowl (which is my norm), or trying to mark them accordingly, I just put them back into the holes they came from before I moved on to the next step. Then I didn't have to worry about what screws went where when I was reassembling.
My biggest advice is to not be afraid of tackling something like this. It's not trivial but it's definitely doable.