I think that it looks nice. But... nothing really catches my eye. Also, your adsense blends in too much with your site and will probably get over looked...
If I were you I would blend the skyscraper with the rest of the sidebar. People are nowadays rather ad-blind and an ad block that clearly stands out from the rest of the connect doesn't get nearly as many clicks as one that blends in and seems to be a part of the content.