~ What handset did you have before and what frustrated you about it?
I had a Galaxy Ace, which drove me utterly bonkers because the internal memory was tiny so it was unable to have more than about 4 apps downloaded. It ran slowly, froze a lot, and the camera never seemed to take decent photos no matter what I did with the settings. It was my first foray into smartphones having been happy with a very basic camera phone for a long time, and I wished after using it for a few weeks that I'd done more research before choosing it as it just didn't seem very, well, smart ...
~ What was most appealing about the Samsung Galaxy S4 Active?
The large screen, the large internal memory, and the fact it is meant to be very tough - I have a whirlwind toddler who delights in throwing things/dropping things/hiding things, a 10 yr old who likes using my phone for games and taking photos, and a hopelessly clumsy DP who has been through 3 phones this year so far (he hasn't been allowed to touch it yet, the children have though
) I also have a friend with an S3 which I've always liked the look of.
~ What were your first impressions when it arrived and you got it fired up? How was the set up?
I was surprised it seemed so shiny and thin, I think I was expecting something more like one of those rubber coated radios that builders have
As soon as I plugged it in to charge and the screen lit up I was really impressed by the display and quality of the screen. Its far beyond what I was used to from my previous handset, much much crisper and clearer with richer colours.
Set up was completely painless. Everything transferred fine, I had to get my SIM cut down to a micro SIM before being able to finish setting up but a nice man on the market in town did that for me (and drooled over the phone a bit too)
I can't quite believe it'll stand up to much dropping or underwatering - it just goes against everything I know about expensive technology - but I am willing to trust Samsung on this!
~ What features have you used so far? What's your opinion of these?
Used the camera, lots. Most of the pictures are coming out really good but I'm having some trouble getting anything black to photograph well in low light - flash or no flash. This isn't something I'd usually notice but its been Hallowe'en and Bonfire stuff galore here recently and I couldn't get a good picture of DD (10) in her cat outfit at all. I suspect however that there will be a setting I can change to improve that, I just haven't found it yet!
Loving the forest themed alarm I've set up - I've actually timed it for before DS (3) wakes, specially so I can have a gentle awakening in advance of the toddler day starting. This is what passes for relaxation now I have children 
Downloaded heaps of apps now that I've got the space to do so - the Guardian, FB, Ebay, mobile banking, weather, all the obvious ones and then a star gazing one, relaxation sounds, CBeebies for DS and one called My Horse for DD. No MN app here though, I know from past experience its a bit rubbish (sorry MNHQ) but have the mobile site bookmarked on the homescreen. Customised everything, set up different sounds for everything - it felt like 'mine' really fast which I love.
DD has asked me to say that her favourite thing of all so far is the bead of light on the lock screen which moves around if you hover your finger over the screen. I like this too, it entertains me more than it ought to, but I wouldn't go as far as to say its my favourite thing 
Not yet tried it underwater as the bath plumbing is out of order but MNing from the bath is something I am massively looking forward to as soon as its all fixed.
~ What about how the phone looks and feels in your hand?
Feels light and easy to use despite the size. I did think it would be a bit big in one hand but actually its not. I do have to say that I am having trouble with the side button placement - its so hard to avoid hitting the volume button when going for the power button and vice versa. I think its something I'll get used to and my fingers will learn not to do with time but its quite frustrating at first.
Like the different coloured LEDs to tell me different things.
I've bought it a nice purple gel case and a screen protector which give me a bit more peace of mind over the fairly high chance of it being dropped!
~ Any additional comments
Everyone who has seen it loves it, including my die hard iPhone lover of a younger brother.