Part of the change for us is that we upgraded to newer Fire TVs at the same time as we moved over to YTTV. So it may be hard to pin down exactly what is attributable to the service and what is due to the device. YTTV is way faster but it may just be because of the newer Fire TV stick. On common devices (like a tablet), I've been more impressed with the YTTV app than Vue. They have some cool features for sports events on certain channels where you can catch up on highlights of a game between when you last tuned in and now (or just jump to live of course).

DVR interface for YTTV is better, and you can apparently keep the recordings for longer. When skipping forward or back on a recording, it shows previews of the content - so it is easier to jump to the end of a commercial break. It's much easier to specify exactly what you want to record and to search for what you've recorded. Say, if I want to record all BYU football games, I can actually choose that option when setting up the recording. For Vue, I just have to record all college football games and then manually search through those to find the BYU game. With YTTV you can specify both - and a specific recording can be categorized in multiple ways.

Guide seems better for YTTV. For live tv, the app will show previews of the current live programming.

One thing I haven't been able to find in YTTV is the ability to select a lower playback quality. With Vue I could specify a lower playback quality in the app so that I could save on data when away from wifi.