Mirage buff

Even then, you have to wait. It's effective, but in moments where your team needs help and you want to shoot someone, you are simply just waiting. 

Mirage's ult feels like its got serious downsides when used offensively or defensively - I've personally nearly stopped using it in general.

-Edit: Not quite sure why it's not a good idea to allow us to cancel the ult at any point we seem fit.

Totally agree. His invisibility needs to be more "invisible" since it IS his ult and you can't use it always. In my opinion he should be more invisible and maybe be able to use items and fire from stealth. Firing from stealth would immediately break it but it would give you an edge instead of not being able to do anything and be very much visible if you know what to look for.

Puts you in a situation of, I used my Ult, my most powerful ability, to simply be a sitting duck getting blasted. 

Defensively it's weaker than wraiths phase walk as she can't take damage at all.

Offensively it's nice to at least see the enemies, but you can't do anything until it finishes. I've actually sat next to the enemies a couple times for a couple seconds just waiting until I can finally shoot.

Simply give us the option to cancel it when we want, via pressing the ult again or shooting. The fact you can't do anything, not even reload, is painful.