I did a lot of reading about the various options and basically narrowed it down to IS and Bodyguardz. I went with the invisible shield for both protection of my ipad and iphone4.
I purchased mine through an australian distributor who were absolutely terrible to deal with. They never reply to emails, and are rude when they do. Shipping took 11 days to get 1 state over, which is absurd in Australia. Their website was invisibleshield.com.au so I thought I was purchasing direct from the company, but alas, even the US company didn't take responsibility for their australian counter part. BAD FORM!
Anyway, with this colouring my judgement, I fitted the full body protection on both ipad and iphone4.
Iphone 4 has the little side protectors and I put some of those on after the front and back. Firstly, it really isn't that hard to put on - spray the fluid everywhere and then put it on and squeegy it all out - yes its a bit scary to have fluid near your device, just make sure you've got a towel or something nearby to soak it all up ASAP.
What I didn't like about the quality of the IS is 2 main things.
1. The quality control is terrible. The little bits are not perfectly cut from the corners, which means you have to CUT the very corners of them to free it from the rest of it. Totally substandard considering the price it costs to manufacture these vs the cost we are all paying for them. This could result in you either trying to pull it off (Which I did initially) and stretching it beyond repair, or having little crap tabs all over your phone which will act as little areas where your fingers can lift the protector off. Not very good here.
2. Orange peel effect. OK, so when you purchase it, you think, how bad can it be! Well, it looks like you just sneezed all over your phone - yes, sneezed quite evenly, but still - what a lot of crap. People talk about it giving you good grip on the phone, but that is a total load of Bs. I never dropped my iphone holding it before I had the protection on anyway, so not a huge consideration for me. My friend has the bodyguardz, and its silky smooth.
3. The deal breaker for me was the perfectly vertical rainbow lines that arise on your screen! Its most evident on a white background, and looks like you've got a faulty screen. I freaked OUT thinking that I got water in my phone or something, but then had a read online, and it appears that these rainbow lines are quite common with the invisible shield and are exaggerated by the quality retina display.
I have emailed the company about this and obviously they haven't replied (As their customer service is an abomination) and have said that I will give it a week to see if it irons itself out, and if not, off it comes. I've got a bodyguardz on standby as my friend has it, and its really really nice.
Hope this helps - what I found out was that there are lots of reviews on the internet, and lots of scratch tests etc, but in real, usability, liveable scenarios, the invisible shield really gets a thumbs down from me so far.