I wouldn't worry about it too much. You're never going to please everyone. If we look at the past several tales you guys have published, most have been solid hits, and even the debate about "Sci-Fi or not" is usually prefaced with "But I really enjoyed this".
In my case, I found the tale an interesting portrayal of companionate love as a cetacen might see it. I thought Ishmael was a robustly developed character, and I shared his frustration over the antagonist's (and yes, that's what she is in this story, when you think about it) inability to respect him or acknowledge him on a deeper level than one might regard a loveable pet. In her defense, though, I think she misinterpreted his affections to be plutonic.
The most interesting thing to me, though, is how people are pegging it as old-fashioned. I strongly disagree with this point of view. The tale was far ahead of its time, and is a testament to Silverberg's risk-taking. This story's fairly heavy sexual content strays close to sexual encounters across species lines. The fact that this was picked up in the 70's echoes the sexual liberation of that time, but even so, one wonders what the reaction of the reader base was when it arrived.
There's much to like. As a literary peon, I hesitate to criticize one of the greats, but I will say that the section with Ishmael roving the ocean, heartbroken, for days fell short of imparting the emotional weight I believe was intended. Rather, the section feels condensed -- perhaps due to over-zealous word count reduction -- and feels disjointed compared to the rest of the tale. Furthermore, Ishmael succumbs to virtually no penalties for this neglect of his duties, which wouldn't be a problem if it weren't for the fact that Ishmael -- and the author -- don't make a big deal out of that (at least, that I can remember). It would have been a perfect spot to have Ishmael complain about how he isn't even regarded on the same level as a human worker, as his getting off easy is indicative of his treatment as an amusing beast.
Overall, the story invokes much thought, involves a juxtaposition of reality as we know it, with dolphins proving more mature in many ways than mighty man, and the future-tech is everywhere. I call it science fiction, and even if it isn't, I don't care.