The line getting in is never an issue - the problem is getting back into Spain. You will eventually but it can be a major PIA. I suspect the latter differs day by day based on who knows what - specific political issues or if the immigration agent had a fight with his wife or ?

You can see the "Rock" better from a distance, which is about all one needs, unless you're a Brit. The Guardia Civil have a tendency to slow traffic down, both into and out of Gibraltar.