Portugal, is it worth it

A bit puzzled by your question. Is this a guided tour, or are you on your own? How many nights would you be staying? What would the itineraries be for each option?
All that being said, I loved visiting Portugal.

As you are already questioning a combined country trip, I think the answer is quite evident. I would suggest sticking to Spain for anything under 2 weeks. For 3 weeks, I would say Spain and one major Portuguese city.
But, you don't say how long the tour is, or you travel style. Some just want highlights, other want something more I depth.

Much depends on the time you have available and what you want to see in Spain. Spain's really large, and there are key cities all over. You can't see much of the country in 2 weeks. You can't see all of it in 2 months.

One other relevant fact: The ground-transportation links between Spain and Portugal are not numerous, so it can be really awkward to combine the two countries on one trip.

Portugal is totally worth visiting! However, I don't think it is ever worth it to rush from place to place on vacation; what's the point? Do another trip focusing on Portugal. We did 5 weeks there and it wasn't enough.

Thank you for everyone's responses. The trip we were thinking of taking is a 9 day tour group which has a set itinerary. There were several reviews which say that it felt rushed with very little time to be by yourself and lots of time in the bus. We do like to have downtime for shopping and exploring. Hope this helps.

That does sound awfully rushed, indeed.

I took RS Best of Spain tour back it back with his Best of Portugal tour. That was just over a three week experience providing a relaxing but fulfilling time. I can’t imagine what a nine day itinerary might entail for both countries. There was very little that I would have excluded.

No a nine day trip Portugal Spain is like a reconnaissance mission