Like every game GURPS has its strong points and its weak points.
I'd like to start with its strong points, where GURPS is amazing
1st High verisimilitude mechanics for combat
2nd Highly detailed and flexible charter generation
3rd Cinematic movie style combat especially for Gun Fu settings.
4th Time Travel. GURPS can handle any time travel setting you can imagine, probably better than they native rules can. If you like the rules from Continuum or Dr. Who or Time Master or whatever you can use any of them or all of them if you feel crazy.
5th Subtle magic systems. GURPS Thaumatology and its predecessor GURPS Voodoo which along with GURPS Spirits I wish would be updated cover the genre better than any other RPG. The only game i know that comes close is Eden Studios Witchcraft written by C.J Carella who wrote GURPS Voodoo . Go figure.
The Return of Planescape? - Curious. There is a brief note on this 'countdown' at Enworld.
15 hours ago