Basic question...I got Legend of Grimrock in my bundle with Ultima Underworld and Wizardry and am very surprised at how good it is. I'm tempted to purchase the sequel, but I play on a laptop. Minimum system requirements are often deceiving. So, in short, I play LoG on low settings and it runs perfectly. Would it be reasonable to assume I could run the sequel just as easily on low, or are the graphical updates pretty substantial??

It's basically the same engine, although Grimrock 2 has a lot of outdoor areas. Naturally, in these areas there'll be a lot more rendering required ofcourse, since you can see pretty far away.
I compared the system requirements of both games and Grimrock 2 only seems to be a teeny little bit higher, so I doubt you'll have any problems since you can run Grimrock smoothly.

To be perfectly safe, you should check the minimum requirements yourself and see if your laptop will pull it off. But if I were you I'd take the gamble. Grimrock 2's awesome. :)

If you meet the minimum requirements then you should be okay, as long as there's nothing else running at the time. (Kill off everything other than your firewall; the various 'helpful' utilities and quicklaunchers that typically take over computer task bars nowadays can have a big impact on game performance.)

It went on sale for 4 hrs tonight and I just couldn't resist. From a test run on the beach it might be a microscopic bit more sluggish but nothing that can't be tolerated in a grid-based game. Certainly playable and I'm looking forward to slowly working my way through both of these games.

Well, from my experience & setup (whccih run LoG1 good to OK (last level)), the LoG2 later out side areas are sluggish to unplayable. Seems to be a not uncommon problem (http://www.grimrock.net/forum/viewtopic.php?f=21&t=7984).