Eratta did change the 88’s to being transportable on the Trucks from North Africa expansion so they can be moved now. They are tricky to use and work best on open and desert maps due to the long lines of sight (LOS). But if you are not at those range 10+ shots your likely better off with the Pak 40 as an ATG. If you are playing certain year restrictions the 88’s are nessessary to level the field like in the desert campaign. The only thing the Germans had for a while that could stop a Matilda was the 88 ATG.
Transporting the 88 is tricky also as they are both Large units and cannot occupy the same hex unless the gun is loaded. The truck must enter in the movement phase and load the gun right away otherwise the hex will be overstacked with 2 large units and subject to penalty under the revised rules. When unloading they must enter the unloading hex in the combat so it may unload and move out the the hex before it becomes overstacked in the movement. Guns must be loaded and unloaded from transport in the movement phase but move on there own in the combat phase.