I've been playing it as my main spec and enjoying it a lot. Skill cap is high and I'm making more than a few mistakes but I'm improving and I'm competitive with other dps of similar ilvl for the moment, I do worry about scalability however.
Any class' scalability comes primarily from how well it uses seconday stats. SV hunter gains very little from them.
Haste doesn't affect DoTs, only GCD & ability cooldowns.
Crit doesn't have any interaction beyond it's basic mechanic. Eagle's Bite can't crit either.
Mastery was doubled and is still weak.
Essentially, when a DPS class is favouring versatility (where much of the value of the stat is defensive), something is wrong.
Also, oddly the spec currently favours Tenacity pets because Mastery only procs extra Mongoose Bites off pet Special Attacks, not auto-attacks, and Tenacity pets have more Special Attacks. Even pet taunt can proc this which is more than a little bit silly!
The spec needs some tweaks to give it greater benefit from at least one, preferably two of these secondaries.
I'd suggest that Mastery instead procs off pet auto attacks (and perhaps also from Lacerate ticks) and haste increases DoT tick speed. Crit can be the "bad" stat but should still be able to crit on the ticks from Eagle's Bite.
An alternative might be for Crit to have some cooldown reduction interaction e.g. Critting with a Mongoose Bite reduces the cooldown of Aspect of the Eagle by 2-3s.