Really underrated game - reputation around here was single-handedly destroyed by Volourn coining the term 'sozzy' and using it repeatedly until it caught on.
Not that it's a 'great' game or anything. But for an expansion pack, that's doing something really different to the base game, it should have been something that the Codex loved. Even with the shitty 2 room dungeons and all. Just the oldschool setup of starting out as nobodies, exploring this big map with no starting aim other than getting rich, finding a bit of a story along the way once you're a fair way in (but still in the 'I'm an adventurer who wants to get rich' vein, not the 'I'm the chosen one' vein), much better crafting system, setting up trade routes - and again, it's an expansion pack, cheap like an indie game. It's the kind of thing where you'd expect that there'd have been a solid Codex fanbase. I've never seen one guy tear apart a game's rep like that since Skyway (before the discovery of 'I've only played KoTOR 7 times' destroyed him, and any future possibility of a Skyway or a Volourn coming in and getting taken seriously when they do that - even Mondblut, who generally has a ton more credibility in these parts than either of those guys, is basically dismissed these days as 'well, he's just a combatfag, so of course he'll hate X and love Y'.)
And the shitty engine isn't any explanation. We loved MotB because the PS:T fans (myself included - I'm pro-MoTB, it's awesome) were able to unite into some kind of Voltron mech that could fend off the forces of Volourn and Skyway, even when they were making entirely legitimate criticisms of how shit the engine is. The engine in SoZ is still shit, but it's by far the least shit implementation of it - it incorporates improved versions of the best AI mods to make party and caster management bearable, gives a far better zoomed out camera, and does everything it can to redeem the shitty engine. Which isn't much, but still - if the engine was the deal-breaker, it should have been a much bigger deal-breaker with MotB.
Even NWN2 itself didn't get as much hate as SoZ, and SoZ is leagues better than that game. The Voltron explanation is the best I can come up with. MotB had the old PS:T fans unite into something more powerful than the individuals involved, whereas SoZ had us divided into those shitty lion and tiger mech toys that were always really over-priced because mum and dad never let me buy them all to make Voltron and so they fucking sucked, because unless you had them all they were just 2nd-rate transformers, and shit, even the Constructacon transformers had the decency to each be individually ok Transformer toys, that you can turn from car into robot even if you didn't have enough of them to build Devastator. FUCK YOU MOM YOU SHOULD HAVE GOT ME TRANSFORMERS FOR MY EIGHTH BIRTHDAY LIKE I ASKED, NOT VOLTRON CRAP!!. We just couldn't overcome the forces of Volourn and Skyway combined in that form.