Sure. However, it is important to know that the feeling towards the magic systems in works can vary a lot between individuals, and my answers might be inaccurate for you.

1. Rules and limitations
Positive: Fullmetal Alchemist. It provides taboos and principles of Alchemy, as well as stories related to following the rules or going beyond and braving the consequences.
Negative: Iron Kingdoms: Full Metal Fantasy. The magic can be used in combats, but not in other scenarios since there are no rules to direct magic users and stop them from spamming.

2. Unique and memorable
Positive: Simon Snow. It has a creative magic system where common sayings, song lyrics, and pop culture references are used to cast spells, and more well-known ones can improve the effect. 
Negative: The Marvel Cinematic Universe. It can be exciting to give each hero a unique suite of powers. However, this sometimes makes the story themed like a mess of ideas stuck together in a hurry, making each of the powers less memorable.

3. Internal logic
Positive: The Inheritance Cycle. The magic system works more like a programming language, and the conservation of energy between casting a spell and taking the same action without magic is also talked about a lot.
Negative: Vampire: the Masquerade. The Thaumaturgy rules lack a consistent logic to separate different sets of paths and rituals, making it difficult to talk about what makes a path special with logical reasons.

4. Tied to the world-building
Positive: Alex Stern. The society is heavily influenced by the magic system, with eight different societies each specilize in different magic, the depravity caused by magic, and dark rituals described in detail.
Negative: Fate/Stay Night. It actually has explained how the Holy Grail War is kept secret reasonably. However, as the effect and collateral damage of fights become much greater in the animes, the fact that nobody in a modern society has noticed this also becomes a little weirder.

5. Characters and conflict
Positive: Godless. Magical ability is not only a benefit, but also a sign of infection from something corrupted by a dead god that can cause a horrible death, putting the character into a crisis.
Negative: Middlegame. The characters tried solving major problems with magical math formulas, but the process is not well explained with too many terminologies not introduced in detail. This makes the turning point less satisfactory and exciting.
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