I think companions are great now. Sure Nico Okarr nukes everything for me in the starting area but that's because the starting character don't have much to show for at that point. This far I haven't felt that my companions have overshadowed me later on in the game. They are very helpful and I'm glad they made them more streamlined. Now I don't have to spend as much time gearing them as my own character and when I grow tired of one I don't have to gear up another one (sure you could make sets for all types of stats in legacy bound gear and swap out but to me that isn't anything fun).
I agree though that a 2 minute long uptime and 5 minute cooldown seems a bit over the top for heroic moment. I think the cooldown is fine, but maybe to limit the uptime to 1 minute would feel more balanced? On the other hand I think you could leave it at 2 minutes and make a longer cooldown. That would let players have 2 minutes of really feeling heroic, which seems to be like a nice thing.