It even harder?
EDIT: Also, how long would you say it is? it took me 21 hours to beat the first one (according to steam, so there might be some idle time in there)
Exoddus is probably as long if you just run past everything and save no mudokons but if you don't then maybe 2x to 3x as long. (There are 300 Mudokons in this one, but you now have the ability to have a group follow you instead of just one at a time.)
It does have a number of levels that are considerably harder than the hardest parts of the first game. Also there are a ton of secret areas (look for the bottles of Brew laying about the level) which are usually small but super hard.
In my opinion, Exoddus is the most fun of the two games so if you liked the first one then definitely try it.