It's good, but not as good as Berserk. Berserk is definitely more epic in scale, but that's to be expected since it's got so much content.
Ubel Blatt has similarities and some differences, such as the shota being a gary stu since childhood, whereas Guts trained himself to be that raw, Shota isn't human, etc. Both are about revenge. Much more fanservice in UB(ratio wise). Much more development in Berserk(again, a given).
UB is like Berserk dumbed down. Still an enjoyable read, since it's about a shota Guts chopping things apart in the name of revenge.