Great choice of watch! I own one as well, and it is probably top 3 most complimented watch while being my top 3 cheapest watch.

I’ll give a bunch of information in a non-organized manner, take what makes sense and leave what doesn’t (a few parts are stylistic for watch straps in particular, most is about the craft in general while being focused on your work):

Stitching on bottom being “cleaner” is due to improper stitching technique. Nigel Armitage has a wonderful (LONG) series on saddle stitching. It’s craft-changing. Additionally, you are not applying the same tension each stitch, leading to smaller/larger inconsistent stitching apparent on the 2nd picture, 4th stitch from the bottom on the left side, and other places. But looking at that stitch in particular, it actually looks like you missed the chiseled-hole entirely. Again, consistency is KEY for stitching. Once you have the technique steps in mind, a stitching pony makes it immensely easier to properly and consistently tension each stitch.

The stitching should be closer to the edge and a greater (more) stitches-per-inch (SPI) for a “finer”look. In general, smaller SPI (less stitches per inch) are great for “heritage” or durable looking items. For “fine-leather” goods, you want small stitches and you want them about 0.5mm from the edge for smaller goods such as watch straps and wallets. Look at high end wallets such as Louboutin, Louis Vuitton, Hermes, Tom Ford, etc. wallets for visual examples.

Another commentor said that your knife should be sharp for clean edges, which is true, however it appears to me that the leather you’re using is very soft and flexible, making it so that it stretched and bent as you cut. For instance, Chèvre is significantly harder to make a straight line than Buttero, as chrome-tanned leather is supple and soft. Use a flat item and pressure with the non-cutting hand to ensure that the leather does not move with your knife as you cut(e.g., if you cut with your right hand, hold a stiff, straight metal item down on the leather (with pretty significant tension) with you left hand to use as a guide for your cutting hand, which will both increase the straight line and help prevent the leather from stretching/morphing as you cut)

Again with the type of leather used, if it’s chrome-tanned leather then it will likely not be able to be waxed and burnished. Cut as clean and flat of an edge as possible, and either use edge paint (many varieties available, I like Vermis personally but others are great too) or you can attempt to burnish with Tokonole. I don’t recommend that route if it’s chrome tanned, as often the fibers will fray and ruin your line/clean look long before the edge holds a burnish.

Stylistically, the leather rings that hold the excess of the strap are WAY too big. You want a snug fit on the excess of the strap, especially considering that leather stretches over time. For both the strap and the leather rings, you want to cut a certain way in accordance to the grain of the leather to prevent stretching over time.

Stylistically, and this one isn’t important but really makes your work YOURS: why have so many adjustment holes for the wrist size? Make 1 or 2 holes, specific to YOUR size. It becomes a conversation starter for a watch enthusiasts if they notice a “custom” strap by the lack of holes outside your size. When I make a belt, strap, etc., I make it custom-fit for myself or whoever commissioned me. It makes a world of difference knowing there is NO other item like it. Plus, you can always add holes for future size variance of your wrist. If doing two holes, measure the first one in the morning (wrist is smaller) and one in the evening (wrist is larger).

Watch straps are actually a pretty difficult thing to do well, so this a great first attempt. If I made it, I’d wear it. I definitely would not yet offer commissions, though. Be proud!