I just started a new game and cleared the first 2 Areas.

I took the Goblin as the first summon because i thought...having someone to pick locks would be wise...but...all locks seem to require a special key anyway.

Are there locks to pick later on...or is only special use of the Gobo stealing a few gems during the battles?

Many thanks...

it seems that he's just a bit to weak compeared to the other summons if there's no real need for his lockpicking.

There are some key sequences that can destroy the key(s) if you use them in the wrong order/locks. I don't know whether the goblin would be able to help out in those cases, though.

Assessing minion strength isn't an entirely straightforward process because there are a lot of variables: equipment quality (particularly weapons, but the rest of the kit matters too), which is mostly drop-dependent; creature level and what point various abilities appear or improve (many minions are late bloomers in this regard, and the goblin seems to be one of them); the synergies you have between specific sets of minions (some of which likewise don't develop until later), etc.

The goblin can be used to open doors you muffed up using the wrong key - but his success roll seems to be quite low. There was one sequence where I had three silver doors but I had only found two silver keys. The goblin managed to unlock the third door. Likewise there is a bug on floor 9-2 with the knight key (if you save and leave, it relocks but you lose the key). My goblin managed to re-unlock the door. Overall he's not the best in my party but he's not bad per-se just not the greatest as a front-liner.

While I know this thread is a year old, I just thought I'd chime in on the Goblin as others may have picked this game up during the sale as I did. Lock-picking is not his strong suit; I did not get any locks picked by him and any thievery options ended with him confused. However, the Goblin was an essential component to my victory on Hard mode since his skills in combat are outstanding. The blinding effect of smoke bomb is really helpful early on to avoid damage, and the choking powder later on coupled with extremely high agility (buffed by items, skill trainer, and natural increase) meant he always moved first; it really made some tough battles manageable to easy. The only downside is the low HP and defense, so use the skill trainer and hope to find some good accessories and armor and this character will help you out too.