Hello
I'm not sure to well understand your question. If you mean what are strong and weak points of the Telemac system, you shoud make a glence on the forum where you can find feedbacks of users from allover the world.
Since I'm a member of the developping team, I will say that Telemac-Mascaret is the best set of hydraulic codes :)
In a nut shell, remember that free, open source, industriel, intensively parallel, forum, free assistance... are between strong points. the inextistence of a interactive GUI could be one of the weakness. Thus, I invite you to use it to assess it objectively :)
With my kind regards
Riadh