May not appeal to all, but nice overhaul if you like Final Fantasy style exploring.
But what's nice about this exploring feature is that it tweaks and puts previously neglected skills like Survival, Spot and Listen to good use, making the ranger and druid considerable choices finally. Talking about character choices, importing in your epic-level Weaponmaster is gonna spoil your adventure big time, just so to warn you, plus, it will really spoil your chances at the Team Feat minigames anyway.
Some things to note would be that it strangely focuses on trading (not stocks, ha) but in terms of merchants-on-foot. And... arrows/bolts, there's tons of them. Well, in other words, Storm of Zehir may only appeal to hardcore fans of Neverwinter Nights and fans who don't mind an alternative way to enjoy the series.