Android Lollipop, while looks pretty and polished, is buggy on the Nexus 5. There is a long list of issues, however the ones I'm facing are the slowdowns, frequent app crashes and faster battery drainage.
But it appears that the wait won't be that long until many, if not all, of those issues will be fixed because Android 5.1 is going to come out in the coming months. Funny thing is that it would initially be coming out with Android One devices. Those are the ones aimed at developing nations, this comes with less premium looking features. It makes sense to release it with these devices because the performance impact of these known issues would be much more pronounced with them than the Nexus line of devices.
Google might release it for the Nexus 6 shortly afterwards or at the same time because it is their number one premium device, however I doubt the Nexus 5 users will be treated similarly. Same thing happened with Android 5 as well, where it took about 3 months for the Nexus 5 to receive the over-the-air update. Many people would say that it is to balance the server load, but this is Google we are talking about. Plus, the Nexus line of devices' market share is insignificant compared to other brands.
While Google hasn't released any official announcements about the 5.1 update, many websites (here's one) have published about the alleged change log and even the build numbers of the firmware for different Nexus devices. Thus, the launch is imminent. It's sad that Google hasn't issued any details about it, not even a timeframe. Bad Google, bad!
Although the OTA update might be delayed for the Nexus 5, in sure you would be able to update manually by downloading the the official firmware from Google servers. Despite not wanting to go through that manual upgrade process again, I will definitely take that because I'm so eager to get my Nexus fixed. I guess the thought is mutual between every Nexus 5 user.