Undeniably, Hydras are one of the most awesome vehicles for the Imperial Guard. It's the ideal killer for AV11-AV12 vehicles and a couple of them have high enough rate of fire to convincingly stun lock an AV 13 tank (fantastic against Predators).
They are also quite easy to protect. I run a squadron of two, using the Forge World models. I just need to park a chimera in front of one (no LoS blockage for the main guns and if placed correctly secondary gun will be OK too) and I instantly get 4+ cover for the lot. They have an amazing range (72'') so I usually deploy them way back so I don't worry about meltas usually until turn 3. And they are also cheap as chips costing 75 points each. They are very often the MVPs on my games. I think every Imperial Guard army should have a couple.
