In my experience, the best tower defense games are ones that have gripping gameplay, regardless of the way it looks. Some of the best TDs out there offer very simplistic graphics, but smooth flowing waves, good maps, and, most importantly, towers that don't suck, especially after upgrading.

Appreciate the transparency, but don't get rushed. I am very anxious for this release, but would hate to have to pass on it due to unplayability. Stay the course, and keep up the good work.