The font here is pretty small (I think 8 pt). So make sure you can read this size before you buy it. The biggest print I could find on a Spanish-English Bible was in the HCSB-RVR (which I think uses a 10pt). The HCSB-RVR is also better (I think) if you're more on the Spanish side, and want a slightly easier English translation.
Also, the footnotes for the text are in the back of the Bible. So they're out of the way, but more difficult to access quickly. Since verses are lined up next to each other, they are easier to compare, and it's easier to find the verse you're looking for. New paragraphs are marked by a little paragraph icon (which aren't necessarily the same for ESV and RVR).
If you're not too comfortable with Spanish, you might want to get a NIV-NVI Bible, since the Spanish in there is easier, and more like what Spanish speakers talk in North America. But the RVR is still the most popular Spanish translation today. Another option would be to see if any parallel Bibles are available with the RVC or NBLH. RVC is made by the guys who make HCSB (updated to CSB). NBLH is made by the guys who make NASB. Both of these Spanish versions are more modern and don't use the "vosotros" form of Spanish.
Be aware that the Spanish RVR relies on different manuscripts than the ESV. The English and Spanish aren't translations of each other. Differences in translation can happen because Spanish translates differently from Hebrew/Greek, but also because the manuscripts consulted were different. Footnotes would help in this area, but they are not that detailed.
I bought these bibles to use with several Hispanic families that recently started to attend worship with us. They seem to appreciate having the two languages side by side. One of the men is older and speaks almost no English. I think he will use this to help him learn both more about Our Lord and also the English language. Glad for that reason I did not get the King James Translation!