I made a better comparison, even though the games really cannot be compared.
Blockland
+ Great multiplayer experience
+ Nice network API
+ Great add-on system
- Glitchy physics
- Mediocre lighting
- Ugly textures
Minecraft
+ Survival is awesome (SO MUCH TO EXPLORE :D)
+ Cool mods
+ Appropriate textures
+ Nice lighting engine (as of Beta 1.3)
- Terrible network API (a Blockland server hosted on a 5-year old home PC is faster than a MC server hosted on a real network server.
Well, I tried.