It's a little hard to say. It's not like Stryd tells you straight out that you're running inefficient or not. It gives you numbers. I attached an example of my morning run today with some short 30 sec intervals. Things that I might be able to take from this:
- First set of intervals have been OK in power, worse in pace because of the wind
- The faster I run the less form power (also see FP ratio; watts to keep me upright and in line) I have to use which I guess points to the fact that there's quite a bit gap between my running form at easy pace and interval pace (this probably is completely normal though)
- Ground contact time is OK, could be better though (but apart from the intervals it was an easy run so yeah...)
- Cadence is low (don't need Stryd for that, watches have that already. Also I'm quite tall and it was mostly an easy run so might still be OKish)
- Leg Spring Stiffness did not significantly decline which probalby means no fatigue has set in
- Compared to other runs my RE Ratio steadily improves (used to be 0.33 and is now 0.30-0.31 for easy runs; I got faster for my easy runs so that alone makes me run more efficient)
- My Leg Spring Stiffness is OK but it's more about how it develops in the long term and there I see no progression. Probably would benefit from plyometrics or hills
- I'm trying to learn what difference shoes make but haven't had enough runs in different shoes

OR
- Could all be BS and it's just the way I run and that's as efficient as I can be at the moment ;)

There are Stryd podcasts and Youtube videos concerning possible analysis of the data, you might wanna have a look at that. Hope that helps