I think the criticisms of ToB are valid, but I still had a lot of fun with it. Even if it was a bit rushed, for me it feels like everything is rapidly escalating towards the big final climatic encounter, so thematically it works. There are also some really fun encounters.
I haven't tried SoD yet. I am not sure if I ever will. I don't need an interim chapter between BG 1 and 2. I have had so long to head canon that period of my Bhaalspawn's life, I don't really want anything that contradicts that.
If Beamdog ever made a completely new, unrelated FR series using the Infinity Engine, I would almost certainly buy that instead. That would actually be pretty cool. I am generally not into retro gaming, but I find that the IE games have aged well. I could play a new one.
I disliked ToB, but it was precisely for the reason that I very strongly prefer lower level games and not because of any quality issues with ToB. I just simply start losing interest in a game once the characters in the game (PC, companions, NPCs) become god-like (and this has been true for all games: the DA games, TES games, Witcher, everything).
As a sidenote for you, Beamdog has very strongly ruled out making any new games using the IE because they don't see the point of using an engine that is a serious coding pain in the ass to work with and when there are other engines that are so much better (their words). They do currently have a new unannounced game they're working on, for which they have confirmed that it does not use any existing IP and that it uses the Unreal 4 engine.