@Windjunkie
The main objective of the beginner phase is to perfect your form in all 4 lifts, and take advantage of a phase what is commonly called on the Internet as "newbie gains".
If you are new to barbell training, you will notice how your lifts linearly progress and make quite solid jumps in a relatively short time period. You'll also notice you're putting on muscle, since you don't have much body fat you can notice that your muscles are growing at a rather decent rate (this was my only favorite part about being skinny as a teen, I could see my tiny frame grow and to stay motivated is quite easy when the progress is noticeable as compared to the difficulty some people have in losing weight). This is the "newbie gains" phase.
There will be a point in your routine in which progress will stall. This will be due to either poor mechanics in your form that you haven't fixed yet OR you've simply tapped out the end of your "newbie gains" phase. If it is the latter, you've reached a point where the weights have gotten so heavy that 5 sets of 5 is just insane and your Central Nervous System is fried.
If you progress is stalling due to breakdown in form/technique (and you can tell the difference, in all four of the lifts; you can actually
feel it out and tell the difference due to failure in technique or the weight being simply too heavy), you have to simply relearn the lift through another method or resource until it stalls from being too heavy while doing 5 sets of 5.
If your form after all this trial/error during your beginner routine is fine and you stall just due to not being able to recover fast enough or it's just too damn heavy to do damn 5 sets of 5 (there'll be a point where the weights are just too heavy to squat and deadlift on the same day) then you can reevaluate what your goals are. Do you like the way you look? Do you want to improve your appearance and physique OR did you catch the lifting bug and you decide to see how strong you can get (Advanced Strength Training include a lot of "fun" rep schemes to continue increasing your numbers)?
Chances are, and very high, that at the end of the beginner phase you will look more muscular and you'll be significantly stronger.
It's really up to you what route you go then. You can either pick an intermediate/advanced barbell program that addresses strength but leans towards the bodybuilding side OR you can pick one that's just solely focused on getting stronger. Either way you now have a fantastic base of strength to do about anything you want, hell I had a friend who got into gymnastics right after he finished running Stronglifts 5x5 for a year; he said it definitely helped.
Jim Wendler and his 531 programs are worth looking at. He has program for bodybuilders, power lifters, military, senior citizens you name it. His books are worth the buy as he has vast experience in programming efficient routines addressing specific goals.
Greyskull LP is a good intermediate program to look at as well, alows you to customize efficiently.
