I love Opi because of the massive selection the brand has to offer.
Normally I do two coats just to be safe and make the colour last longer but it also helps the nail polish to look much more effective and eye popping.
Unfortunately depending on what Opi you get they chip quite easily which is why it is best to do 2 or more coats. The drying process is quite long also so it does take patience.
Opi is prices are a bit more then your average pharmacy nail brand but you are paying for appearance and quality.
Of course the price reflects the quality in this instance. I have a range of their nail lacquer ranging from sparkly to nude to brights and those horrible cracking polishes. Only reason I didn't like the crack is because I think the concept was tacky and your nails looked like they were chipping. The actual product did exactly what it was meant to do. For the rest I do love them they apply so well, they are a good consistency the bottle is a great shape and the brush i long enough to get right down to the bottom. They don't dry up fast inside the bottle. They don't last as I would like maybe 4 days but this is about the longest a polish will last on me apart from sally hansen xtreme wear (lasts a week). They do go on really nicly and arn't bumpy or anything but they do they long to dry. Max coats would be 2.
The sparkly lacquer though you need at least 4 to really build it up and then removing it is literally hours which is quite common for sparkly polish. The actual polish once dried does look amazing
Tips: use 2 coats wipe the brush slightly before applying and use a soft file on your nails to make them last longer