Long fangs are excellent, and it is largely believed that rigging out 4-5 with
MLs is the best way to go. As for thunderwolf cavalry/wolves, these are nice but overall fail. Having
Ld 6 means even the biggest wolf squads can get completely screwed by Leadership Psychic powers and the like, or just fall back way too much in general. also they can NEVER be scoring units even if you throw in canis wolfborn to make them troops. thunderwolf cavalry are overpriced and die way way way too easily for being able to field max 15 of them. also, both these two take away valuable fast attack slots that could be better used for speeders or even Skyclaws (although many will argue these too fail)
SW cheese is in the fact that Grey Hunters cost 1 point less than regular marines, have one more attack (since
GW decided they needed a bolt pistol, boltgun AND
CC weapon), and get counterattack (thus deterring the "lets assault them first after they deepstrike!"). They also can each carry a Wolf Standard, giving them (once per game) a re-roll of ANY (and this includes saves) rolls of 1 during an assault phase (for a mere 10 points too!). This combined with the equally cheap long fangs/scouts (which are the ONLY scouts worth taking in the game...meltas behind your tanks anyone?) and some of the best librarians in the game (Rune Priests) make them monsters. Wolf Guard are a versatile unit and Logan Grimnar is pretty sick. However, their unique
HQs, while awesome, are usually too expensive or too squishy vs the common powerfist/klaw. but when you run some of the best troops in the game, the sons of fenris dont care.
oh and for all your friend's
SW worries, have him/her check out:
http://space-wolves-grey.blogspot.com/ for literally EVERY SINGLE THING EVERY you could want to know about playing the space puppies to their max