Re: How is the new JB customs?
These are my limited experiences thus far:
* SG-bound
Drove out from JB this morning, surprisingly no jam. Maybe the authorities there open more booths so as to project an efficient image for the time being.
After clearing the immigration, I was travelling anti-parallel to the incoming vehicles from SG. Their right lane was filled with buses, leaving only the left lane free for cars, so that might be a bottleneck. Hopefully when the road routings are fully completed (currently cars going to JB have to drive through the old complex then loop up to the new CIQ fyi), it wouldn't occur.
* JB-bound
As for the design of the new CIQ, do note that the lanes (esp at and around the passport-stamping area) are quite narrow, drive with care. There are 1 or 2 moderately steep upslopes also (already have gash marks while in the trial period!), lowered cars driving slowly shouldn't encounter a problem.
Also, when merging together after pass-stamping, there are a few area IIRC where the rounded kerb blends in with the concrete, ie. the vertical sides have no coloured markings.
The part where the officers inspect your boot, watch out for the raised area just before it, as it blends in with the road surface.
So the conclusion is: driving in/out through the new CIQ, just drive slowly, check out the sights and familiarize properly in the meantime first.
HTH.