I'm going to sum my opinion up with this:
Yes PortAventura has atrocious operations, Im not doubting that for a second, Furius Baco and Stampida are incredibly rough and yes they do a lot of staggered openings, however on that last point, the Spanish in general are very laid back and PortAventura Park is never busy at 10:00am anyway. Another reason for the staggered openings is the Park is open until 12:00pm for most of the year meaning at the very least you will have 12 hours a day to ride on attractions not opening until lunch.
But for me as a guest and enthusiast the above faults don't out way the positives. PortAventura has continued to grow and expand year after year introducing two new themed areas to PortAventura Park, new attractions, doubling the size of the Waterpark, has built two new high quality Resort Hotels, 3 Golf Courses and Beach Club. Entertainments has gone from strength to strength presenting new major shows on a yearly basis, creating a parade and extremely successful events including White Nights, Oktoberfest and Christmas. The Park is always kept in an immaculate condition with world class themeing, and for the 20th Anniversary alone is carrying out a huge list of improvements and new experiences, to further develop the Park. Not to mention the addition of a 6th Hotel and 3rd Park in 2016.
So for me, I don't know about others, two rough coasters, the fact there isnt a path between two hotels, staggered openings and slow throughputs are minor inconveniences compared to the larger picture. But I can honestly say PortAventura has expanded more than any other European Park over the last 5 years and continues to do so.