I'm a beginner at Latin, and I don't have much in the way of knowledge of other dictionaries to serve as comparison, so readers should take my opinions in this light.
This dictionary has been helpful, but regularly enough there are words I cannot find. My understanding from others is that it is a decent dictionary, but not the best. I believe Lewis and Short is considered the best one out there, but is pricey.
Another shortcoming of this dictionary -- and all print dictionaries -- is that the words you're looking for will only be listed in their primary declensions or inflections. For example, you won't find "dominis" because that is the plural dative/ablative of the singular nominative "dominus", which is listed. Likewise, you won't find "amavi", the perfect indicative first person singular active of "amo", the form in which it (as all verbs) is listed, that is present indicative first person singular active.
What I've actually resorted to using is Wiktionary. It's not perfect, but you can look up many words in their various declensions and inflections and find them instantaneously. It's a great resource. Of course, it's not subject to critical standards in the same way other dictionaries are, but I've found it to be accurate and sometimes better than my dictionary. Apparently there is also a Lewis and Short online dictionary, but I haven't checked it out. Either way, it's useful to have a printed dictionary to back up or verify what's found online, and also in situations where you can't be online. This one's OK.