Summary: This is a rugged, highly functional English-Spanish and Spanish-English translator that has worked flawlessly for me over the eight months I have owned it. I recommend it highly for anyone with a beginning or intermediate level of Spanish who will be visiting a Spanish speaking country. The most common negatives raised in the comments are true: spoken word quality is poor (but volume is fine), and the screen is not backlit. In my daily use of the translator, I have not found these to be a problem at all.
I am an American who is currently living near Madrid, Spain for a year. I have a low intermediate level knowledge of Spanish. As a result, I frequently find myself running into unknown words I see on food packaging, menus, advertisements, newspaper articles, etc. The ability to whip out the translator and quickly get a translation is invaluable, and I now make sure I have the translator with whenever I leave the house. I would replace it instantly if I were to lose it.
There are two big advantages of this translator over a small pocket dictionary (which I also have). First is speed. Almost always I can look up a word faster using the translator than using the dictionary. Second is looking up conjugated verbs. With a dictionary, you need to know (a) that the word you're looking up is a verb conjugation, and (b) what the root verb is. For irregular verbs, or more advanced tenses, this can be a challenge. Type in "tuve" on the translator and you get "tener". Look up "tuve" in the dictionary and it's not there. In a similar vein, the translator will suggest a long list of possible words if you misspell a word (great for typing in a word you heard on TV).
That all said, this unit does not replace a full dictionary, which can provide more subtle shades of meaning. I own both, and find that each has its uses. However, I use the Franklin translator many times a day, while the more complete dictionary is used much less often.
Typing on the keyboard is easy. The keys are chiclet style, and have a spongy feel. When held in both hands, it is easy to use both thumbs to quickly type in words. Occasionally the unit will miss a key due to fast typing, but misspelled word correction feature means the unit will typically let you pick the word you intended without having to got back and correct your entry.
The Franklin translator isn't perfect. The further you get away from mainstream words and into specialized vocabulary, the more frequently the translator will not have a good translation or will not have the word. Like any translation, you will need to exercise personal judgment when using the provided translations. Additionally, the translator has a bias towards South American Spanish. For example, translate "restrooms" and you will receive "servicios" and "baño" but not the common (in Spain) "aseos" (for which it doesn't have a translation).
The translator has a ton of features, including an English dictionary, thesaurus, unit and currency converter, clock, calculator, flashcards, and some learning games. I don't use these features very often, though they all appear to be quite solid.
As other reviewers have noted, the screen is fairly small, six lines of text using default settings. It is possible to make the text smaller, and cram more information on the screen. I don't use this feature, since it's harder to read when I'm out and about. There is a page down feature that lets you scroll through materials quickly. The screen is also not backlit, which I have not found to be a major problem. Yes, it will be hard to read in dark places, but so will a pocket dictionary. It is possible to adjust the screen contrast, which might help in low light situations.
The ability to have the translator speak a word from the dictionary seems like it should be useful, but it really isn't. Spanish has very regular pronunciation rules, so once you have those down, word pronunciation is usually not an issue. I just don't find myself wanting to use this feature that much. The pronunciations I have heard are very mechanical sounding, and not especially good. I like the earphones that came with my unit.
Battery life is excellent -- the unit seems to run forever on just two AAA batteries. I have operated the unit successfully using NiMH rechargeable AAA batteries (some electronic gizmos don't like the lower voltage levels of NiMH batteries).
The unit is a little larger than I would prefer, but still fits nicely into an adult pants pocket.
I have found the unit to be very rugged in daily use. It has traveled in my pocket on many excursions, been played with by my young kids, been dropped on the floor a few times, and still keeps on ticking.