I’ve not built the Trumpeter MiG-21, but I’ve seen inside the box and I can safely say that they don’t seem to have missed anything in the way of detail.
The instructions are very clear and have photos of MiG-21s from the Verlinden “Lock On” book of the MiG-21 MF
From all I saw of it in the box and all I’ve heard about it from those who’ve built it, I’d say you’re getting your money’s worth in that kit.
If you do buy it, I strongly recomend the Verlinden “lock On” book and the 4+ Publications book on the MiG-21. They’re both great books well worth the money and probably all the reference you’ll need to get it looking right.
I built the Mig-21MF and although it is not Tamiya quality, it is a good value for the money. It goes together well, but some parts are too thick (wing trailing edges,etc)
but if you put some extra effort into it , you will have a stunning model.
Do a web search using google. I just did and found several reviews on the model. All I put in the search criteria was “trumpeter+mig-21+review” I think you’ll find a lot of information.