I hope the other boss fights aren't as bad as the first one in Deus Ex. The first boss fight really sucked, it felt poorly implemented and designed.
If you spent your proxies on stealth attributes and want to go the non-lethal route, it is very difficult. His gun kills you way too fast. And staying out of his sight is easier said than done.
The most frustrating part of this game so far has been the first boss fight. They should have given alternate ways to defeat him other than just going head on or hacking turrets which ended up being a big pain to do.