The first to get the update (starting May) will be the Ascend Mate7, which was released in September 2014 with Android 4.4 KitKat on board. Next will be the Ascend P7 and Ascend Mate 2, both of which are scheduled to get Lollipop starting July. Interestingly, the Mate 2 will be updated directly to Lollipop from Android 4.3 Jelly Bean. As for the mid-range Ascend G7, this will be updated to Android 5.0 starting September.
Besides Lollipop, all updates will also (probably) bring a refreshed Huawei Emotion UI (aka EMUI), which is currently at version 3.0.
Needless to say, Huawei isn't as fast as other manufacturers when it comes to delivering Lollipop updates (some companies, like Motorola and Samsung, started updating select devices last year). However, it's still nice to see that Huawei isn't ignoring its important handsets.