Looks like it just adds more travelling NPCs. It's really just a question of how crowded you like your roads, really a matter of taste. Having said that, some of the posts suggest that this mod may be buggy.
But I do like crowded roads myself, so instead I can vouch for:
http://www.nexusmods.com/oblivion/mods/32747/ (some merchants, some wander off-road too)
http://www.nexusmods.com/oblivion/mods/18251/ (All sorts, some dangerous. Comes in several different versions, think I'm running an earlier one, must update...)
I've found that both of these work well with each other and with Tamriel Travellers, no game instability I can see. Think I had to clean them both though. Only thing is that sometimes the road traffic turns into a virtual procession, but I find that quite funny, especially when some bandits decide to join in too...