One thing that occurs to me is that the temptation to add too much can be very strong. For example in my opinion they gussied up the Orion slaver ship and the Tellarite ship a bit too much, The Tellarites (seen in the mind meld sequence) don't look quite like TOS Tellarites. Mind you in some cases it's not a bad thing. In some ways STC can show things TOS could only do if they'd had feature film resources, such as showing people on the hangar deck. If STC were to do a Gorn I'd like to think that maybe, just maybe, the Gorn costume could be somewhat upgraded from the original. But that said I have no interest in seeing the ENT bastardized version of the Gorn. Ditto any overly greebled Tholian ships. In the first episode "Pilgrim Of Eternity" I didn't think the realm artifact belonging to Apollo's people looked quite right in looking very cgi. Essentially I hope they don't go down the road CBS did with overdoing a lot of the enhanced f/x and change for change's sake.
We have to keep in mind that in some ways STC is able to do enhanced f/x and post-production that constraints prevented TOS from doing. That's why we have a gorgeous Doug Drexler cgi model of the Enterprise
that can be viewed from any angle whereas the original 11 footer couldn't really allow that. I really like how Drexler did the infamous gridlines in keeping them so very subtle. Here we have an enhanced viewing experience and yet the gridlines are not that visible. It also has to be said that after the episode is complete apparently they add a slight measure of film grain to all the footage similar as was done with the new f/x sequences in the TMP DE. So on viewing the footage looks really clean yet in enlarged stills and screencaps you can see the film grain. A very nice subtle touch to get the desired look.
Seeing what Drexler did with the Enterprise
I can only salivate on what he could give us if STC ever shows us a TOS Klingon Battle Cruiser. SWEET!!! (-: