The good news is that French grammar is not as ugly as that of Russian or German (not to mention Irish grammar, a matter of such hideous difficulty that the only way to get people to learn it is to force them to begin at age 5, when they are too small and powerless to offer effective resistance). The same kinds of things tend to be difficult in French as in Spanish. If I were to name the most evil aspects of each, the list would be essentially the same:
1. prepositional verbs
2. connecting phrases
3. order of pronouns
4. use of the subjunctive
The first of these, based on my experience with German, Spanish, French, and Russian, seems to be something that tops the difficulty chart in every language. In German, for instance, you can start with a perfectly straightforward verb like "nehmen" (to take), and, depending on the preposition that you add as a prefix, you can change the meaning to - and this is just a partial list - to gain weight, to lose weight, to take over, to do something, to try, to film, to record, to absorb, to incorporate, to exclude, to behave, to earn, to see, to infer, to gather, to assume, to accept, to send away a red-headed stepchild with a flea in his ear, to deprive a pregnant grandmother of her social security check, etc etc etc.
Russians have a slightly different focus where prepositional verbs are concerned. For some odd reason, most of the relevant grammatical ugliness is squarely localized in the domain of verbs of motion. But, let's be clear, this is an area where Russian breaks out the heavy artillery. You or I, in our innocent naivete, might simply "go" across the river to grandmother's house. To your average Russian, this straightforward declarative statement would be risible, for its lack of nuance and telling detail. Just how did you "go"? Were you alone? Were you on foot? Were you in some kind of vehicle? Was that vehicle propelled by an engine? A beast? A quadruped? An even-toed ungulate? Was this the first time you've been to grandmother's house? Did you cross a river, or other body of water? Were you wearing a hat? Had you just had a fight with your loved one? Did you go at dawn? Were the birch trees in bloom? What was your spiritual state of mind? How did your cat feel about the journey? You'd better have an answer to all these questions before you even think about opening your mouth. Otherwise you will attach the wrong prefix to your verb of motion, and expose yourself to the snickering and ridicule of native speakers, who apparently have nothing better to do with their time than to attach importance to such matters.
If you have suffered through the bewildering infinity of meanings that can attach themselves to Germanic prepositional verbs, and struggled with the metaphysical aspects of motion in the Slavic psyche, the relative simplicity of matters in the Romance languages may come as a welcome surprise.
But don't let down your guard. The trick in Spanish and French is to know the right preposition to go with the verb in question. Problem is, each language has a list the length of your arm and then some. And until you master each and every verb on that list, you will never feel at home in the language. What I'm suggesting here is that that list will be one of the very last things that you do end up mastering.
Prepositional verbs suck. They are hard in every language.
This post has gone on long enough. I will return to items 2-4 in subsequent entries, and will also provide some thoughts on difficulties that appear to me to be specific to French.
Prepositional verbs in Irish are too horrible even to contemplate. Start with the fact that any verb worth its salt takes a prepositional form (Irish people are not "hungry" - "a hunger is upon them"; they don't "like" things - "a liking is with them", they don't "have" things - "things are to them", and so on). Then add the hideous variation that any given preposition combines with each of the personal pronouns to give a bizarre set of so-called prepositional pronouns, each set of which has to be memorized, along with all the associated verbs. If you tried to instruct your cat about the byzantine complexities of the resulting satanic brew of grammatical atrocities, the SPCA would be knocking on your door within the hour. But Irish children as young as 5 are tormented thusly with no intervention from the authorities. All the time. It's a truly horrifying state of affairs.
Take a gander here to get some sense of the true hideosity of it all.