Pros:
Tower Park occupies a large, hilly, wooded piece of land right in the small city of Greenville, MI (which happens to be the birthplace of the Meijer grocery store chain). The paved Fred Meijer Flat River Trail winds through the park. The park is a ski/sledding area in the winter, but at other times of year it looks like the main activities here are walking/jogging the trail and disc golf. The holes mostly play well away from the trail, and it is labeled as OB on the holes where it could come into play.
Tower Park DGC has mostly tight but fair wooded holes - which is very common for courses in this area. There are a good mix of left-turning, straight, and right-turning holes, which will force you to shape your shots. Again, not uncommon for this area. What sets this course apart from most of its wooded peers is elevation change and length.
Let me start with the elevation. After a fairly flat first three holes, the elevation really starts coming into play on #4. It's a 396' par 4, down a steep wooded valley then back up, ending higher than you started. From there it's up or down or up and over or through more valleys for most of the remaining holes. The baskets are well placed, creating several risk/reward opportunities.
#7 is another memorable hole. It's a 231' throw that plays up a steep hill, with a sharp turn to the right about halfway through. #9 is probably your best chance for an ace, but beware. It's a slightly downhill 174' throw with a below-average number of trees between tee and basket - but overshoot or fade too far left and your disc is going down a steep incline. You'll be lucky to make it back for par, and may not even find your disc if it fades well left.
This course also has more variation in length, and more length overall than many courses in the area. Five holes run in the 400' range or greater, with three of those being legitimate par 4s. The longest hole here is #13, which plays 550' but feels more like 700'. It's not as steep of a slope here as on some of the other holes, but a steady uphill grade from start to finish.
After 16 wooded holes, you'll finish your round throwing up the ski/sledding hill for #17, and back down for #18. The openness of these last two holes adds a little more variety to the overall course and provides a chance to really air out a couple throws.
The tees here are fantastic. Large, new concrete tee pads and color graphic tee signs displaying hole layout, hole number, distance, and par. Trash cans at many tees as well.
The baskets are Chainstars and all in good shape, although they can be tough to see in the woods. There is a practice basket next to the first tee (not at parking lot).
Kiosk between the parking lot and first tee, displaying a copy of the same map uploaded here. Take a photo of the map or download the one here in case you need it.
There are Next Tee signs at many baskets/between holes pointing you to the next tee and also naming what hole number that next hole is. This turns out to be important, see Cons.
Cons:
The biggest con here is the layout/flow. I appreciate the effort to create fantastic holes all around the available space, but there is a LOT of walking between holes here. The longest walk is between #6 and #7 - I would estimate this trek at somewhere between 750' and 1000'. If you park in the main parking lot (roughly at the center of the course), you will also walk across the road you drove in on four different times. Holes #1-3 are on the east side of the road, #4-12 on the west side, #13-16 back on the east side, and #17-18 west side. I'm not too concerned from a safety standpoint - it's a 25 mph road and not particularly busy, and well away from all baskets. Also, I want to be clear that between the map and the Next Tee signs navigation isn't that challenging. I think that given the layout they chose, the designers did a good job with the signage and navigation - but it's just a lot of walking. A couple more Next Tee signs to kind of reassure me that I'm still on the right path would be appreciated.
Between traversing the hilly holes and the paths between them, this course is a solid workout. That isn't a con in itself for me, but something to be aware of. A few benches at tees would be a nice improvement.
Hole 6 is an awesome downhill throw, but it's a little bit dangerous. There is a trail crossing the fairway maybe 100' off the tee. I don't think this is the main Fred Meijer trail but it seemed like it could be populated, and it's kind of a blind throw across it. Also there is private property behind the basket that an errant throw could potentially find (would have to sail through quite a few trees to get there though).
Other Thoughts:
You could play holes #4-12 to get a shorter 9 hole round, or #1-3 and 13-18 to get a longer 9.
With the addition of benches and maybe a slight redesign of hole 6, this course would be basically maxed out for the land available. I don't feel this course quite has the true "wow" factor to be 5.0 level, but regardless it is a gem! The people of Greenville are lucky to have this right in their backyards. It is worth the 30-45 min drive from Grand Rapids. If you are visiting the area you should check this place out!
Update July 2021: No change to 4.0 rating. I updated some of the verbage above, and added the bits about the practice basket and hole 6's safety issue (both of which I did not notice/appreciate previously). I just played this course on a Sunday afternoon, and did not see another disc golfer. I also haven't heard many local players talking about this course, and there don't seem to be any regular DG events here. I'm not sure if it's the lack of other courses nearby, or why else this course isn't more popular. It may be one of the area's best-kept DG secrets. My recommendation: PLAY IT!