That observation deck is going to be awesome. As will those terraces going up the side of the tower. Seems to be a theme these days among highrises - providing terraced outdoor space to office tenants. And not a bad trend.
In terms of the overall design, the massing and weighting is a little weird and unbalanced, but that kind of goes with the theme of Frankfurt. Many of the towers have irregular massing, mostly due to the shape of the blocks and the lots as a result, so while it looks kind of top heavy, it still fits in to the overall skyline quite well. Which is very fitting for Frankfurt, because a lot of these towers work because they're in Frankfurt, and might not work well otherwise.
At the beginning of the 2000s, Frankfurt was planning a building with a height of 1211 feet and 97 floors.
Unfortunately, these plans were never realized.
Old Millennium Tower (369 m / 1211 ft) www.faz.net
Construction start will not likely be before 2025/2026. Specific timing has not yet been decided upon by CA Immo and will depend on a number of factors including, among others, receipt of building per-mission, decision on ultimate usage mix, and satisfactory market demand resp. pre-leasing ratios.”