I presume the OP is talking here about a reasoanbly serious relationship here and not exactly a casual tourism trip, so absolutely it could be worth it. If the application isn't totally straightforward it can be very worrying and frustrating but I'd hardly describe it as humiliating. I have been through it for my partner.

There are professional immigration advisors who have a pretty good idea exactly what documentation you will need to ensure you're successful. If you get good advisors then they are very worthwhile, even though not cheap, but I think that's more usual for a settlement visa.

The amount of documentation required to sponsor a tourist visa is far far less than needed for a family visa of any kind which leads to permanent settlment here. A letter from you, some basic confirmation of your relationship (e.g. photographs) and your ability to support your girlfriend during her stay would normally be enough, together with a copy of your passport and proof of address. I honestly don't know if filipino applicants have a particularly onerous time compared with those from other countries with a similar level of development, but I would give it a go without employing any advisors or suchlike unless your girlfriend has a chequered past. What is the application fee? It sounds like if you're declined you can give it another shot later, perhaps with advisors and after the relationship has developed further.