General
You need some pictures of the "real thing" (or it's sibling the KaJaPa) to build a unit "in the field". The Revell instructions will build a unit "in the museeum"
Some fine details in the instruction (missile hatch, optics detail) take careful study of the plan. Again a real world picture or three is helpful
The tank builds into the mid (HOT) or late (HOT and night fighting) version. Not the early (SS-11) or the Austrian "command" version
The model itself
Decend fit with some filling needed where the upper hull and the sidewalls meet. The most tricky part is the step down from the frontal hull to the engine deck. Make sure you have filled and sanded that part properly before adding the engine grills
The Missile tube itself needs some filling and sanding in the seams. Depending on what photo source you use it also needs a rim added to the tubes end(s). This may be only present in exercise tubes (The tube in the model is a live one)
The mirrors are fragile (one of mine broke of). And the kit only allows them in the "up" (In use) position. Most pictures showing vehicles in the field have the mirrors folded down against the hull. So I cut them off where the mirror stalk meets the plug on the hull
The hull maschine gun needs to be drilled out on the muzzle to look real
The rear "mounting aid" (a small, grilled plate) needs his grills cut open carefully. It is easy to break and a very small piece to repair.
The tank offers two options for the front "basket" (Used to stow the cammo net when not in use). Only the one with the round railing seems to be in use in germany.
Remember to fix the tracks before you mate the hulls. Unlike the Kanone you can't do so afterwards
Painting
NATO black is NOT black. So using "black" to mark out the camo pattern is a bad idea
Mascol (liquid masking) to mark out the cammo pattern didn't work for me. Trying to pull it off didn't work (after 24h of settling) so I had to use an old brush. That took of some of the paint
I overpainted the model with heavily thinned (30-40 paint to 70-60 thinner) Tamiya paints. Single stroke in one direction, allow some drying time.
After almost two years my 15€ "comes with the compressor" airbrush has died during the build. Damn, I expected it to hold up at least 10 years

Changes and third party stuff
I replaced the towing hooks with resin pieces from Perfect Scale I had. Not a "must have" but I had them around from my "Luchs" build where I managed to loose two of the pieces and PS delivers 8 in a pack for 3€
Replacing the commanders maschine gun should be considered. PS has a better one (Compare the KaJaPa pictures in the BW campaign) than the kit piece (2 for 7€). The Revell one is decend and since I used my last one for a Leopard build (and my dealer is out of stock) I fixed that
PS has a etched/resin set out that replaces the front/rear mudguards, tools and tool holders and rear lights. Designed for the KaJaPa but the two share a common hull. I opted against it since I plan to use heavy cammo netting and I am not sure if the tool holders fit with the changed mounting of the snow grips. This one would be costly (around 17€)
I wouldn't replace the tracks since most is covered by the skirts and the rest will end up in "mud". For a "during presentations" model or a Kanone your milage may vary.