Not every game needs to insanely fast to be considered good. There's plenty of high flow games that are not well regarded. Sometimes non stop action gets dull and often prevents moments in the game from occurring. Personally I think its nice to have a blend of flow and stop and go.
With WOZ there's so many different things to shoot at including a variety of targets, shots that drop into / pass through an area, and 2 upper playfields with their own shots (1 having a hidden shot behind the castle doors). The player can focus on different areas of the game that correspond to specific goals. Want to go after Crystal Ball modes, go for hitting the BALL standups. Want to go for Munchkin modes, then hit the RAINBOW targets to light the upper left mini playfield. Those are are just a couple of the areas and on top of that you can then stack the Crystal Ball and Munchkin modes with other modes for bigger points. Attempting to earn the 4 emeralds throughout a game is a lot of fun as it acts a reward feature for completing goals, something very few games do. Hell, then if you even get the 4 emeralds and reach the Wicked Witch wizard modes you can also go after the 10 or whatever diamonds in the game to reach the super wizard mode.
What I mentioned above is the fun of WOZ and I wouldn't substitute a mini playfield or a mech for another ramp just to add more "flow". What JJP did with WOZ is incredible and hell the game is still receiving code updates 8 years later. WOZ is a modern TZ in my opinion, is loaded with fun toys / mechs, has a ton to shoot for, and has one of the deepest rulesets in pinball. I'm sure some people will disagree and that's cool...but I'll go to my grave saying those things lol.