Today I also picked up a pack of new "button" track (from Walmart for $1.97) to evaluate for use with the Smittsburg International Dragway (a used and modified) Drag Track set I recently obtained.
In general I also agree with Brian that this track looks better than the orange "arrow" track and should stay cleaner without the cut outs in the bottom to allow dirt in. The visual thing I didn't like though, is that the joiner plastic in this packs are blue and shows as a series of blue dots in the track surface. ( I am a fan of the Gulf Racing team orange and blue colors, so I am warming to it a bit already. (20140407 update: I have decided to take the unopened packs of blue joiner track back and exchange it for a Speedo!)
Each of the 4 joiners looks and fits the same. They each have a different #s embossed onto the bottom of "1" "21" "22" "24". The only improvement I can see to make on them - is that there are four uneven "posts" on their bottom side. Most likely, the four mold injection points or keys. They each are random in length, but some do stick out a little farther down than the track support rails do and may cause a miniscule of a bump in the track surface. Being that they are random in length and placement at the four corners a potential side to side motion on the track may be induced. They can though - be easily trimmed with an Xacto knife or a box cutter (which I did) to be even with the designed square support molded into the joiner piece!
Of the four pieces of track - only one has any markings on them. Stamped on the bottom is "CC X 79" and "3373 DP". There does not seem to be a preferred direction indicated, but their is a visible "flow pattern" on the top and bottom of each piece. Look for a ") ) ) ) )" shaped pattern - it is easiest to see on the bottom side. For reasons described below, I choose to use that pattern as the track direction!
The track ends and the walls are uniform in size for the most part, but there is an apparent side to side "crown/camber" built into each of these 4 track pieces. Meaning one side of the track is slightly higher than the other. I can not visually see if it is track base thickness or joiner rail height difference - it is that slight. It does though create a bit of an uneven joint with one side of the track surface being a speed bump and the other a drop off. If the flow pattern is connected as )))) to (((( or (((( to )))))
I aligned the )))) pattern to all point the same direction and this gave the best seam joints - although the track is canted to one side now! This is most evident without the joiners in place.
If you are familiar with trains (both real and models) the term is called super elevation. Usually it is only done in curves. This is where the outside track rail is higher than the inside track rail - causing a slight lean into the curve direction. This allows for safer and faster speeds. You can also visualize this as a banked race track in NASCAR, with the same effect. But since these are straight pieces, it probably will cause cars to drift to the lower side or weave back and forth - if the differing heights are alternated. Some of you may like these elements as they would add a "natural" visual appearance to your racing. And if you primarily run closed tracks set ups (ovals) you can align your track pieces so that the outside wall is always super elevated like a banked track.
The only other physical design problem I did notice with the track pieces is that the interlocking post and button tab do not allow for a fully closed seam gap. There is a slight gap at all the seams. (Previously you could push the old track designs together to eliminate any seam gap and they would (mostly) stay that way or be readjusted. You can still do this manually, but when you take the pressure off - it separates again.
The positive physical design element of the "button" are that they allow the track to be easily taken apart for storage or portability. And best of all you can now suspend the track in the air without it separating. The chamfered edges of the joiner pieces and their locking tabs (nips) also allow for easier and faster assembly.
Overall I think it is a better track design and product and will get more of it for the Drag Track set up instead of using the "arrow" track pieces I already have available.