My impressions about GURPS limitations are:
There are only 4 base stats.
And 3 of them are physical.
Therefore, GURPS concludes that everything that can possibly do with the mind is an INT-based skill.
BS
If you want a durable, dexterous, strong fighter, you gotta pump in too many points that you don't have at creation to distinguish yourself from the normal person (10 in a stat).
If you want an insanely intelligent PC that can be incredible at MOST of the skills (including things like Intimidation), all you need is one stat.
also, the Health stat (which only affect hit points and endurance, basically) is just as expensive to pump up than DEX or INT (the god stats in GURPS).
Therefore, you see a lot of PC's with 10 in Health.
And not too many really strong PC's, since all it does is affect damage.
Add in the fact that a combat-oriented character will by default have less willpower than a bookworm with high INT, and you see the limitations of a 4-Stat system.
Having said that, the game seems much "free-er" with what you can do, and there are fewer preconceptions about characters.
If you get a DM that really knows the rules, so you can just concentrate on role-playing your character and his abilities, then GURPS does many things better than D&D.