well, Canis is pretty cheap in terms of points (a lord in twm with 2 wolf claws costs the same as he does, so you get the saga AND the attack modifying ability for free) however, he has 2 clear disadvantages. 1) Ld8 is pretty big since if you're running things like fenrisian wolves you WILL need to take some Ld tests. the second disadvantage is the lack of an invul save, but this can be somewhat compensated by either sticking him with a TWC unit with SS or in a large unit of fenrisian wolves. He has a large number of attacks and can reroll to hit with good initiative so he should be killing quite a bit before stuff can hit back. Be careful with dreadnoughts though, since you're only S5 and a dread will instant death you.
I actually think the saga is one of the more enticing parts of canis, especially if you run a cavalry heavy army. I think one of the nicer things to play together with canis is Iron priests in TWM with cyberwolves. Having initiative 5 is pretty awesome, and will allow the cyberwolves to actually be quite a threat in combat until the priest hits with the hammer.
being able to take wolves as troops means of course that you can take 3 units of TWC and still be able to take a large-ish bubblewrap unit of wolves. Again, with the saga they can actually be moderately dangerous if your opponent doesn't shoot them up, which leaves your nastier stuff alive and in cover.
One thing I'll stress though is that you NEED some sort of fire support, because otherwise all your pretty TWC won't be able to get anything out of their transports and you'll just get shot to death.
so, if you use him make sure you use his special abilities to maximum effect. If you're not going to be using fenrisian wolves or cyberwolves, you might as well take a double wolf claw lord with belt of russ and saga of warrior born which will cost only slightly more but give you much more value.
hope that helps,
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